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[SelectionDAG][RISCV] Teach computeKnownBits to use range metadata for atomic_load. #137119

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Merged
merged 3 commits into from
Apr 24, 2025
Merged

[SelectionDAG][RISCV] Teach computeKnownBits to use range metadata for atomic_load. #137119

merged 3 commits into from
Apr 24, 2025

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topperc
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@topperc topperc commented Apr 24, 2025 •
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And teach SelectionDAGBuilder to get the range metadata in
visitAtomicLoad.

This allows us to recognize that sign extending a byte load of a
boolean value from memory will produce zeros for the extended bits.
This allow us to remove an AND on RISC-V.

Tests copied from #136502 with range metadata added to i1 cases.
Some of the test effects overlap with #136502, but that patch can't
handle the acquire or seq_cst cases with the Zalasr extension. We
only have sign extending versions of those loads.

topperc added 2 commits April 23, 2025 23:08
@topperc
Pre-commit tests
0b5a200
@topperc
[SelectionDAG][RISCV] Teach computeKnownBits to use range metadata fo…
5abee2b 
…r atomic_load.

And teach SelectionDAGBuilder to get the range metadata in
visitAtomicLoad.

This allows us to recognize that sign extending a byte load of a
boolean value from memory will produces zeros for the extended bits.
This allow us to remove an AND on RISC-V.

Tests copied from llvm#136502 with range metadata added to i1 cases.
Some of the test effects overlap with llvm#136502, but that patch can't
handle the acquire or seq_cst cases with the Zalasr extension. We
only have sign extending versions of those loads.
@topperc topperc requested a review from arsenm April 24, 2025 06:30
@llvmbot llvmbot added the llvm:SelectionDAG SelectionDAGISel as well label Apr 24, 2025
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llvmbot commented Apr 24, 2025

@llvm/pr-subscribers-llvm-selectiondag

Author: Craig Topper (topperc)

Changes

And teach SelectionDAGBuilder to get the range metadata in
visitAtomicLoad.

This allows us to recognize that sign extending a byte load of a
boolean value from memory will produces zeros for the extended bits.
This allow us to remove an AND on RISC-V.

Tests copied from #136502 with range metadata added to i1 cases.
Some of the test effects overlap with #136502, but that patch can't
handle the acquire or seq_cst cases with the Zalasr extension. We
only have sign extending versions of those loads.

Patch is 50.54 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/137119.diff

3 Files Affected:

  • (modified) llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (+34-10)
  • (modified) llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (+2-1)
  • (added) llvm/test/CodeGen/RISCV/atomic-load-zext.ll (+1362)
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index cf88c1f4ae937..092dbf926eec9 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -4382,6 +4382,38 @@ KnownBits SelectionDAG::computeKnownBits(SDValue Op, const APInt &DemandedElts,
     Known.Zero |= APInt::getBitsSetFrom(BitWidth, VT.getScalarSizeInBits());
     break;
   }
+  case ISD::ATOMIC_LOAD: {
+    // If we are looking at the loaded value.
+    if (Op.getResNo() == 0) {
+      auto *AT = cast<AtomicSDNode>(Op);
+      unsigned ScalarMemorySize = AT->getMemoryVT().getScalarSizeInBits();
+      KnownBits KnownScalarMemory(ScalarMemorySize);
+      if (const MDNode *MD = AT->getRanges())
+        computeKnownBitsFromRangeMetadata(*MD, KnownScalarMemory);
+
+      switch (AT->getExtensionType()) {
+      case ISD::ZEXTLOAD:
+        Known = KnownScalarMemory.zext(BitWidth);
+        break;
+      case ISD::SEXTLOAD:
+        Known = KnownScalarMemory.sext(BitWidth);
+        break;
+      case ISD::EXTLOAD:
+        if (TLI->getExtendForAtomicOps() == ISD::ZERO_EXTEND)
+          Known = KnownScalarMemory.zext(BitWidth);
+        else if (TLI->getExtendForAtomicOps() == ISD::SIGN_EXTEND)
+          Known = KnownScalarMemory.sext(BitWidth);
+        else
+          Known = KnownScalarMemory.anyext(BitWidth);
+        break;
+      case ISD::NON_EXTLOAD:
+        Known = KnownScalarMemory;
+        break;
+      }
+      assert(Known.getBitWidth() == BitWidth);
+    }
+    break;
+  }
   case ISD::ATOMIC_CMP_SWAP_WITH_SUCCESS:
     if (Op.getResNo() == 1) {
       // The boolean result conforms to getBooleanContents.
@@ -4407,21 +4439,13 @@ KnownBits SelectionDAG::computeKnownBits(SDValue Op, const APInt &DemandedElts,
   case ISD::ATOMIC_LOAD_MIN:
   case ISD::ATOMIC_LOAD_MAX:
   case ISD::ATOMIC_LOAD_UMIN:
-  case ISD::ATOMIC_LOAD_UMAX:
-  case ISD::ATOMIC_LOAD: {
+  case ISD::ATOMIC_LOAD_UMAX: {
     // If we are looking at the loaded value.
     if (Op.getResNo() == 0) {
       auto *AT = cast<AtomicSDNode>(Op);
       unsigned MemBits = AT->getMemoryVT().getScalarSizeInBits();
 
-      // For atomic_load, prefer to use the extension type.
-      if (Op->getOpcode() == ISD::ATOMIC_LOAD) {
-        if (AT->getExtensionType() == ISD::ZEXTLOAD)
-          Known.Zero.setBitsFrom(MemBits);
-        else if (AT->getExtensionType() != ISD::SEXTLOAD &&
-                 TLI->getExtendForAtomicOps() == ISD::ZERO_EXTEND)
-          Known.Zero.setBitsFrom(MemBits);
-      } else if (TLI->getExtendForAtomicOps() == ISD::ZERO_EXTEND)
+      if (TLI->getExtendForAtomicOps() == ISD::ZERO_EXTEND)
         Known.Zero.setBitsFrom(MemBits);
     }
     break;
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 66bd78af2939c..4b05d89417d2c 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -5150,9 +5150,10 @@ void SelectionDAGBuilder::visitAtomicLoad(const LoadInst &I) {
 
   auto Flags = TLI.getLoadMemOperandFlags(I, DAG.getDataLayout(), AC, LibInfo);
 
+  const MDNode *Ranges = getRangeMetadata(I);
   MachineMemOperand *MMO = DAG.getMachineFunction().getMachineMemOperand(
       MachinePointerInfo(I.getPointerOperand()), Flags, MemVT.getStoreSize(),
-      I.getAlign(), AAMDNodes(), nullptr, SSID, Order);
+      I.getAlign(), AAMDNodes(), Ranges, SSID, Order);
 
   InChain = TLI.prepareVolatileOrAtomicLoad(InChain, dl, DAG);
 
diff --git a/llvm/test/CodeGen/RISCV/atomic-load-zext.ll b/llvm/test/CodeGen/RISCV/atomic-load-zext.ll
new file mode 100644
index 0000000000000..8097179443791
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/atomic-load-zext.ll
@@ -0,0 +1,1362 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=riscv32 -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefix=RV32I %s
+; RUN: llc -mtriple=riscv32 -mattr=+a,+no-trailing-seq-cst-fence -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefixes=RV32IA,RV32IA-WMO %s
+; RUN: llc -mtriple=riscv32 -mattr=+a,+ztso,+no-trailing-seq-cst-fence -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefixes=RV32IA,RV32IA-TSO %s
+; RUN: llc -mtriple=riscv64 -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefix=RV64I %s
+; RUN: llc -mtriple=riscv64 -mattr=+a,+no-trailing-seq-cst-fence -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefixes=RV64IA,RV64IA-WMO %s
+; RUN: llc -mtriple=riscv64 -mattr=+a,+ztso,+no-trailing-seq-cst-fence -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefixes=RV64IA,RV64IA-TSO %s
+
+
+; RUN: llc -mtriple=riscv32 -mattr=+a -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefixes=RV32IA,RV32IA-WMO-TRAILING-FENCE %s
+; RUN: llc -mtriple=riscv32 -mattr=+a,+ztso -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefixes=RV32IA,RV32IA-TSO-TRAILING-FENCE %s
+
+; RUN: llc -mtriple=riscv64 -mattr=+a -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefixes=RV64IA,RV64IA-WMO-TRAILING-FENCE %s
+; RUN: llc -mtriple=riscv64 -mattr=+a,+ztso -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefixes=RV64IA,RV64IA-TSO-TRAILING-FENCE %s
+
+; RUN: llc -mtriple=riscv32 -mattr=+a,+experimental-zalasr -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefixes=RV32IA,RV32IA-ZALASR,RV32IA-ZALASR-WMO %s
+; RUN: llc -mtriple=riscv32 -mattr=+a,+experimental-zalasr,+ztso -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefixes=RV32IA,RV32IA-ZALASR,RV32IA-ZALASR-TSO %s
+
+; RUN: llc -mtriple=riscv64 -mattr=+a,+experimental-zalasr -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefixes=RV64IA,RV64IA-ZALASR,RV64IA-ZALASR-WMO %s
+; RUN: llc -mtriple=riscv64 -mattr=+a,+experimental-zalasr,+ztso -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefixes=RV64IA,RV64IA-ZALASR,RV64IA-ZALASR-TSO %s
+
+define zeroext i1 @atomic_load_i1_unordered(ptr %a) nounwind {
+; RV32I-LABEL: atomic_load_i1_unordered:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    addi sp, sp, -16
+; RV32I-NEXT:    sw ra, 12(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    li a1, 0
+; RV32I-NEXT:    call __atomic_load_1
+; RV32I-NEXT:    andi a0, a0, 1
+; RV32I-NEXT:    lw ra, 12(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    addi sp, sp, 16
+; RV32I-NEXT:    ret
+;
+; RV32IA-LABEL: atomic_load_i1_unordered:
+; RV32IA:       # %bb.0:
+; RV32IA-NEXT:    lb a0, 0(a0)
+; RV32IA-NEXT:    ret
+;
+; RV64I-LABEL: atomic_load_i1_unordered:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi sp, sp, -16
+; RV64I-NEXT:    sd ra, 8(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    li a1, 0
+; RV64I-NEXT:    call __atomic_load_1
+; RV64I-NEXT:    andi a0, a0, 1
+; RV64I-NEXT:    ld ra, 8(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    addi sp, sp, 16
+; RV64I-NEXT:    ret
+;
+; RV64IA-LABEL: atomic_load_i1_unordered:
+; RV64IA:       # %bb.0:
+; RV64IA-NEXT:    lb a0, 0(a0)
+; RV64IA-NEXT:    ret
+  %1 = load atomic i8, ptr %a unordered, align 1, !range !0, !noundef !1
+  %2 = trunc nuw i8 %1 to i1
+  ret i1 %2
+}
+
+define zeroext i1 @atomic_load_i1_monotonic(ptr %a) nounwind {
+; RV32I-LABEL: atomic_load_i1_monotonic:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    addi sp, sp, -16
+; RV32I-NEXT:    sw ra, 12(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    li a1, 0
+; RV32I-NEXT:    call __atomic_load_1
+; RV32I-NEXT:    andi a0, a0, 1
+; RV32I-NEXT:    lw ra, 12(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    addi sp, sp, 16
+; RV32I-NEXT:    ret
+;
+; RV32IA-LABEL: atomic_load_i1_monotonic:
+; RV32IA:       # %bb.0:
+; RV32IA-NEXT:    lb a0, 0(a0)
+; RV32IA-NEXT:    ret
+;
+; RV64I-LABEL: atomic_load_i1_monotonic:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi sp, sp, -16
+; RV64I-NEXT:    sd ra, 8(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    li a1, 0
+; RV64I-NEXT:    call __atomic_load_1
+; RV64I-NEXT:    andi a0, a0, 1
+; RV64I-NEXT:    ld ra, 8(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    addi sp, sp, 16
+; RV64I-NEXT:    ret
+;
+; RV64IA-LABEL: atomic_load_i1_monotonic:
+; RV64IA:       # %bb.0:
+; RV64IA-NEXT:    lb a0, 0(a0)
+; RV64IA-NEXT:    ret
+  %1 = load atomic i8, ptr %a monotonic, align 1, !range !0, !noundef !1
+  %2 = trunc nuw i8 %1 to i1
+  ret i1 %2
+}
+
+define zeroext i1 @atomic_load_i1_acquire(ptr %a) nounwind {
+; RV32I-LABEL: atomic_load_i1_acquire:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    addi sp, sp, -16
+; RV32I-NEXT:    sw ra, 12(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    li a1, 2
+; RV32I-NEXT:    call __atomic_load_1
+; RV32I-NEXT:    andi a0, a0, 1
+; RV32I-NEXT:    lw ra, 12(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    addi sp, sp, 16
+; RV32I-NEXT:    ret
+;
+; RV32IA-WMO-LABEL: atomic_load_i1_acquire:
+; RV32IA-WMO:       # %bb.0:
+; RV32IA-WMO-NEXT:    lb a0, 0(a0)
+; RV32IA-WMO-NEXT:    fence r, rw
+; RV32IA-WMO-NEXT:    ret
+;
+; RV32IA-TSO-LABEL: atomic_load_i1_acquire:
+; RV32IA-TSO:       # %bb.0:
+; RV32IA-TSO-NEXT:    lb a0, 0(a0)
+; RV32IA-TSO-NEXT:    ret
+;
+; RV64I-LABEL: atomic_load_i1_acquire:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi sp, sp, -16
+; RV64I-NEXT:    sd ra, 8(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    li a1, 2
+; RV64I-NEXT:    call __atomic_load_1
+; RV64I-NEXT:    andi a0, a0, 1
+; RV64I-NEXT:    ld ra, 8(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    addi sp, sp, 16
+; RV64I-NEXT:    ret
+;
+; RV64IA-WMO-LABEL: atomic_load_i1_acquire:
+; RV64IA-WMO:       # %bb.0:
+; RV64IA-WMO-NEXT:    lb a0, 0(a0)
+; RV64IA-WMO-NEXT:    fence r, rw
+; RV64IA-WMO-NEXT:    ret
+;
+; RV64IA-TSO-LABEL: atomic_load_i1_acquire:
+; RV64IA-TSO:       # %bb.0:
+; RV64IA-TSO-NEXT:    lb a0, 0(a0)
+; RV64IA-TSO-NEXT:    ret
+;
+; RV32IA-WMO-TRAILING-FENCE-LABEL: atomic_load_i1_acquire:
+; RV32IA-WMO-TRAILING-FENCE:       # %bb.0:
+; RV32IA-WMO-TRAILING-FENCE-NEXT:    lb a0, 0(a0)
+; RV32IA-WMO-TRAILING-FENCE-NEXT:    fence r, rw
+; RV32IA-WMO-TRAILING-FENCE-NEXT:    ret
+;
+; RV32IA-TSO-TRAILING-FENCE-LABEL: atomic_load_i1_acquire:
+; RV32IA-TSO-TRAILING-FENCE:       # %bb.0:
+; RV32IA-TSO-TRAILING-FENCE-NEXT:    lb a0, 0(a0)
+; RV32IA-TSO-TRAILING-FENCE-NEXT:    ret
+;
+; RV64IA-WMO-TRAILING-FENCE-LABEL: atomic_load_i1_acquire:
+; RV64IA-WMO-TRAILING-FENCE:       # %bb.0:
+; RV64IA-WMO-TRAILING-FENCE-NEXT:    lb a0, 0(a0)
+; RV64IA-WMO-TRAILING-FENCE-NEXT:    fence r, rw
+; RV64IA-WMO-TRAILING-FENCE-NEXT:    ret
+;
+; RV64IA-TSO-TRAILING-FENCE-LABEL: atomic_load_i1_acquire:
+; RV64IA-TSO-TRAILING-FENCE:       # %bb.0:
+; RV64IA-TSO-TRAILING-FENCE-NEXT:    lb a0, 0(a0)
+; RV64IA-TSO-TRAILING-FENCE-NEXT:    ret
+;
+; RV32IA-ZALASR-WMO-LABEL: atomic_load_i1_acquire:
+; RV32IA-ZALASR-WMO:       # %bb.0:
+; RV32IA-ZALASR-WMO-NEXT:    lb.aq a0, (a0)
+; RV32IA-ZALASR-WMO-NEXT:    ret
+;
+; RV32IA-ZALASR-TSO-LABEL: atomic_load_i1_acquire:
+; RV32IA-ZALASR-TSO:       # %bb.0:
+; RV32IA-ZALASR-TSO-NEXT:    lb a0, 0(a0)
+; RV32IA-ZALASR-TSO-NEXT:    ret
+;
+; RV64IA-ZALASR-WMO-LABEL: atomic_load_i1_acquire:
+; RV64IA-ZALASR-WMO:       # %bb.0:
+; RV64IA-ZALASR-WMO-NEXT:    lb.aq a0, (a0)
+; RV64IA-ZALASR-WMO-NEXT:    ret
+;
+; RV64IA-ZALASR-TSO-LABEL: atomic_load_i1_acquire:
+; RV64IA-ZALASR-TSO:       # %bb.0:
+; RV64IA-ZALASR-TSO-NEXT:    lb a0, 0(a0)
+; RV64IA-ZALASR-TSO-NEXT:    ret
+  %1 = load atomic i8, ptr %a acquire, align 1, !range !0, !noundef !1
+  %2 = trunc nuw i8 %1 to i1
+  ret i1 %2
+}
+
+define zeroext i1 @atomic_load_i1_seq_cst(ptr %a) nounwind {
+; RV32I-LABEL: atomic_load_i1_seq_cst:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    addi sp, sp, -16
+; RV32I-NEXT:    sw ra, 12(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    li a1, 5
+; RV32I-NEXT:    call __atomic_load_1
+; RV32I-NEXT:    andi a0, a0, 1
+; RV32I-NEXT:    lw ra, 12(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    addi sp, sp, 16
+; RV32I-NEXT:    ret
+;
+; RV32IA-WMO-LABEL: atomic_load_i1_seq_cst:
+; RV32IA-WMO:       # %bb.0:
+; RV32IA-WMO-NEXT:    fence rw, rw
+; RV32IA-WMO-NEXT:    lb a0, 0(a0)
+; RV32IA-WMO-NEXT:    fence r, rw
+; RV32IA-WMO-NEXT:    ret
+;
+; RV32IA-TSO-LABEL: atomic_load_i1_seq_cst:
+; RV32IA-TSO:       # %bb.0:
+; RV32IA-TSO-NEXT:    fence rw, rw
+; RV32IA-TSO-NEXT:    lb a0, 0(a0)
+; RV32IA-TSO-NEXT:    ret
+;
+; RV64I-LABEL: atomic_load_i1_seq_cst:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi sp, sp, -16
+; RV64I-NEXT:    sd ra, 8(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    li a1, 5
+; RV64I-NEXT:    call __atomic_load_1
+; RV64I-NEXT:    andi a0, a0, 1
+; RV64I-NEXT:    ld ra, 8(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    addi sp, sp, 16
+; RV64I-NEXT:    ret
+;
+; RV64IA-WMO-LABEL: atomic_load_i1_seq_cst:
+; RV64IA-WMO:       # %bb.0:
+; RV64IA-WMO-NEXT:    fence rw, rw
+; RV64IA-WMO-NEXT:    lb a0, 0(a0)
+; RV64IA-WMO-NEXT:    fence r, rw
+; RV64IA-WMO-NEXT:    ret
+;
+; RV64IA-TSO-LABEL: atomic_load_i1_seq_cst:
+; RV64IA-TSO:       # %bb.0:
+; RV64IA-TSO-NEXT:    fence rw, rw
+; RV64IA-TSO-NEXT:    lb a0, 0(a0)
+; RV64IA-TSO-NEXT:    ret
+;
+; RV32IA-WMO-TRAILING-FENCE-LABEL: atomic_load_i1_seq_cst:
+; RV32IA-WMO-TRAILING-FENCE:       # %bb.0:
+; RV32IA-WMO-TRAILING-FENCE-NEXT:    fence rw, rw
+; RV32IA-WMO-TRAILING-FENCE-NEXT:    lb a0, 0(a0)
+; RV32IA-WMO-TRAILING-FENCE-NEXT:    fence r, rw
+; RV32IA-WMO-TRAILING-FENCE-NEXT:    ret
+;
+; RV32IA-TSO-TRAILING-FENCE-LABEL: atomic_load_i1_seq_cst:
+; RV32IA-TSO-TRAILING-FENCE:       # %bb.0:
+; RV32IA-TSO-TRAILING-FENCE-NEXT:    fence rw, rw
+; RV32IA-TSO-TRAILING-FENCE-NEXT:    lb a0, 0(a0)
+; RV32IA-TSO-TRAILING-FENCE-NEXT:    ret
+;
+; RV64IA-WMO-TRAILING-FENCE-LABEL: atomic_load_i1_seq_cst:
+; RV64IA-WMO-TRAILING-FENCE:       # %bb.0:
+; RV64IA-WMO-TRAILING-FENCE-NEXT:    fence rw, rw
+; RV64IA-WMO-TRAILING-FENCE-NEXT:    lb a0, 0(a0)
+; RV64IA-WMO-TRAILING-FENCE-NEXT:    fence r, rw
+; RV64IA-WMO-TRAILING-FENCE-NEXT:    ret
+;
+; RV64IA-TSO-TRAILING-FENCE-LABEL: atomic_load_i1_seq_cst:
+; RV64IA-TSO-TRAILING-FENCE:       # %bb.0:
+; RV64IA-TSO-TRAILING-FENCE-NEXT:    fence rw, rw
+; RV64IA-TSO-TRAILING-FENCE-NEXT:    lb a0, 0(a0)
+; RV64IA-TSO-TRAILING-FENCE-NEXT:    ret
+;
+; RV32IA-ZALASR-LABEL: atomic_load_i1_seq_cst:
+; RV32IA-ZALASR:       # %bb.0:
+; RV32IA-ZALASR-NEXT:    lb.aq a0, (a0)
+; RV32IA-ZALASR-NEXT:    ret
+;
+; RV64IA-ZALASR-LABEL: atomic_load_i1_seq_cst:
+; RV64IA-ZALASR:       # %bb.0:
+; RV64IA-ZALASR-NEXT:    lb.aq a0, (a0)
+; RV64IA-ZALASR-NEXT:    ret
+  %1 = load atomic i8, ptr %a seq_cst, align 1, !range !0, !noundef !1
+  %2 = trunc nuw i8 %1 to i1
+  ret i1 %2
+}
+
+define zeroext i8 @atomic_load_i8_unordered(ptr %a) nounwind {
+; RV32I-LABEL: atomic_load_i8_unordered:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    addi sp, sp, -16
+; RV32I-NEXT:    sw ra, 12(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    li a1, 0
+; RV32I-NEXT:    call __atomic_load_1
+; RV32I-NEXT:    zext.b a0, a0
+; RV32I-NEXT:    lw ra, 12(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    addi sp, sp, 16
+; RV32I-NEXT:    ret
+;
+; RV32IA-LABEL: atomic_load_i8_unordered:
+; RV32IA:       # %bb.0:
+; RV32IA-NEXT:    lb a0, 0(a0)
+; RV32IA-NEXT:    zext.b a0, a0
+; RV32IA-NEXT:    ret
+;
+; RV64I-LABEL: atomic_load_i8_unordered:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi sp, sp, -16
+; RV64I-NEXT:    sd ra, 8(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    li a1, 0
+; RV64I-NEXT:    call __atomic_load_1
+; RV64I-NEXT:    zext.b a0, a0
+; RV64I-NEXT:    ld ra, 8(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    addi sp, sp, 16
+; RV64I-NEXT:    ret
+;
+; RV64IA-LABEL: atomic_load_i8_unordered:
+; RV64IA:       # %bb.0:
+; RV64IA-NEXT:    lb a0, 0(a0)
+; RV64IA-NEXT:    zext.b a0, a0
+; RV64IA-NEXT:    ret
+  %1 = load atomic i8, ptr %a unordered, align 1
+  ret i8 %1
+}
+
+define zeroext i8 @atomic_load_i8_monotonic(ptr %a) nounwind {
+; RV32I-LABEL: atomic_load_i8_monotonic:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    addi sp, sp, -16
+; RV32I-NEXT:    sw ra, 12(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    li a1, 0
+; RV32I-NEXT:    call __atomic_load_1
+; RV32I-NEXT:    zext.b a0, a0
+; RV32I-NEXT:    lw ra, 12(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    addi sp, sp, 16
+; RV32I-NEXT:    ret
+;
+; RV32IA-LABEL: atomic_load_i8_monotonic:
+; RV32IA:       # %bb.0:
+; RV32IA-NEXT:    lb a0, 0(a0)
+; RV32IA-NEXT:    zext.b a0, a0
+; RV32IA-NEXT:    ret
+;
+; RV64I-LABEL: atomic_load_i8_monotonic:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi sp, sp, -16
+; RV64I-NEXT:    sd ra, 8(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    li a1, 0
+; RV64I-NEXT:    call __atomic_load_1
+; RV64I-NEXT:    zext.b a0, a0
+; RV64I-NEXT:    ld ra, 8(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    addi sp, sp, 16
+; RV64I-NEXT:    ret
+;
+; RV64IA-LABEL: atomic_load_i8_monotonic:
+; RV64IA:       # %bb.0:
+; RV64IA-NEXT:    lb a0, 0(a0)
+; RV64IA-NEXT:    zext.b a0, a0
+; RV64IA-NEXT:    ret
+  %1 = load atomic i8, ptr %a monotonic, align 1
+  ret i8 %1
+}
+
+define zeroext i8 @atomic_load_i8_acquire(ptr %a) nounwind {
+; RV32I-LABEL: atomic_load_i8_acquire:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    addi sp, sp, -16
+; RV32I-NEXT:    sw ra, 12(sp) # 4-byte Folded Spill
+; RV32I-NEXT:    li a1, 2
+; RV32I-NEXT:    call __atomic_load_1
+; RV32I-NEXT:    zext.b a0, a0
+; RV32I-NEXT:    lw ra, 12(sp) # 4-byte Folded Reload
+; RV32I-NEXT:    addi sp, sp, 16
+; RV32I-NEXT:    ret
+;
+; RV32IA-WMO-LABEL: atomic_load_i8_acquire:
+; RV32IA-WMO:       # %bb.0:
+; RV32IA-WMO-NEXT:    lb a0, 0(a0)
+; RV32IA-WMO-NEXT:    fence r, rw
+; RV32IA-WMO-NEXT:    zext.b a0, a0
+; RV32IA-WMO-NEXT:    ret
+;
+; RV32IA-TSO-LABEL: atomic_load_i8_acquire:
+; RV32IA-TSO:       # %bb.0:
+; RV32IA-TSO-NEXT:    lb a0, 0(a0)
+; RV32IA-TSO-NEXT:    zext.b a0, a0
+; RV32IA-TSO-NEXT:    ret
+;
+; RV64I-LABEL: atomic_load_i8_acquire:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    addi sp, sp, -16
+; RV64I-NEXT:    sd ra, 8(sp) # 8-byte Folded Spill
+; RV64I-NEXT:    li a1, 2
+; RV64I-NEXT:    call __atomic_load_1
+; RV64I-NEXT:    zext.b a0, a0
+; RV64I-NEXT:    ld ra, 8(sp) # 8-byte Folded Reload
+; RV64I-NEXT:    addi sp, sp, 16
+; RV64I-NEXT:    ret
+;
+; RV64IA-WMO-LABEL: atomic_load_i8_acquire:
+; RV64IA-WMO:       # %bb.0:
+; RV64IA-WMO-NEXT:    lb a0, 0(a0)
+; RV64IA-WMO-NEXT:    fence r, rw
+; RV64IA-WMO-NEXT:    zext.b a0, a0
+; RV64IA-WMO-NEXT:    ret
+;
+; RV64IA-TSO-LABEL: atomic_load_i8_acquire:
+; RV64IA-TSO:       # %bb.0:
+; RV64IA-TSO-NEXT:    lb a0, 0(a0)
+; RV64IA-TSO-NEXT:    zext.b a0, a0
+; RV64IA-TSO-NEXT:    ret
+;
+; RV32IA-WMO-TRAILING-FENCE-LABEL: atomic_load_i8_acquire:
+; RV32IA-WMO-TRAILING-FENCE:       # %bb.0:
+; RV32IA-WMO-TRAILING-FENCE-NEXT:    lb a0, 0(a0)
+; RV32IA-WMO-TRAILING-FENCE-NEXT:    fence r, rw
+; RV32IA-WMO-TRAILING-FENCE-NEXT:    zext.b a0, a0
+; RV32IA-WMO-TRAILING-FENCE-NEXT:    ret
+;
+; RV32IA-TSO-TRAILING-FENCE-LABEL: atomic_load_i8_acquire:
+; RV32IA-TSO-TRAILING-FENCE:       # %bb.0:
+; RV32IA-TSO-TRAILING-FENCE-NEXT:    lb a0, 0(a0)
+; RV32IA-TSO-TRAILING-FENCE-NEXT:    zext.b a0, a0
+; RV32IA-TSO-TRAILING-FENCE-NEXT:    ret
+;
+; RV64IA-WMO-TRAILING-FENCE-LABEL: atomic_load_i8_acquire:
+; RV64IA-WMO-TRAILING-FENCE:       # %bb.0:
+; RV64IA-WMO-TRAILING-FENCE-NEXT:    lb a0, 0(a0)
+; RV64IA-WMO-TRAILING-FENCE-NEXT:    fence r, rw
+; RV64IA-WMO-TRAILING-FENCE-NEXT:    zext.b a0, a0
+; RV64IA-WMO-TRAILING-FENCE-NEXT:    ret
+;
+; RV64IA-TSO-TRAILING-FENCE-LABEL: atomic_load_i8_acquire:
+; RV64IA-TSO-TRAILING-FENCE:       # %bb.0:
+; RV64IA-TSO-TRAILING-FENCE-NEXT:    lb a0, 0(a0)
+; RV64IA-TSO-TRAILING-FENCE-NEXT:    zext.b a0, a0
+; RV64IA-TSO-TRAILING-FENCE-NEXT:    ret
+;
+; RV32IA-ZALASR-WMO-LABEL: atomic_load_i8_acquire:
+; RV32IA-ZALASR-WMO:       # %bb.0:
+; RV32IA-ZALASR-WMO-NEXT:    lb.aq a0, (a0)
+; RV32IA-ZALASR-WMO-NEXT:    zext.b a0, a0
+; RV32IA-ZALASR-WMO-NEXT:    ret
+;
+; RV32IA-ZALASR-TSO-LABEL: atomic_load_i8_acquire:
+; RV32IA-ZALASR-TSO:       # %bb.0:
+; RV32IA-ZALASR-TSO-NEXT:    lb a0, 0(a0)
+; RV32IA-ZALASR-TSO-NEXT:    zext.b a0, a0
+; RV32IA-ZALASR-TSO-NEXT:    ret
+;
+; RV64IA-ZALASR-WMO-LABEL: atomic_load_i8_acquire:
+; RV64IA-ZALASR-WMO:       # %bb.0:
+; RV64IA-ZALASR-WMO-NEXT:    lb.aq a0, (a0)
+; RV64IA-ZALASR-WMO-NEXT:    zext.b a0, a0
+; RV64IA-ZALASR-WMO-NEXT:    ret
+;
+; RV64IA-ZALASR-TSO-LABEL: atomic_load_i8_acquire:
+; RV64IA-ZALASR-TSO:       # %bb.0:
+; RV64IA-ZALASR-TSO-NEXT:    lb a0, 0(a0)
+; RV64IA-ZALASR-TSO-NEXT...
[truncated]

@topperc topperc requested a review from s-barannikov April 24, 2025 06:31
arsenm
arsenm reviewed Apr 24, 2025
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llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp Outdated
Comment on lines 4402 to 4405
if (TLI->getExtendForAtomicOps() == ISD::ZERO_EXTEND)
Known = KnownScalarMemory.zext(BitWidth);
else if (TLI->getExtendForAtomicOps() == ISD::SIGN_EXTEND)
Known = KnownScalarMemory.sext(BitWidth);
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Avoid repeated getExtendForAtomicOps, switch over it? We should get rid of it eventually

s-barannikov
s-barannikov approved these changes Apr 24, 2025
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LGTM

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -4382,6 +4382,38 @@ KnownBits SelectionDAG::computeKnownBits(SDValue Op, const APInt &DemandedElts,
Known.Zero |= APInt::getBitsSetFrom(BitWidth, VT.getScalarSizeInBits());
break;
}
case ISD::ATOMIC_LOAD: {
// If we are looking at the loaded value.
if (Op.getResNo() == 0) {
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(minor) Possibly could be an assertion, chain result is not a part of data flow

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I was keeping consistency with ISD::LOAD. Maybe we should change all of them at once?

@topperc topperc merged commit f261f14 into llvm:main Apr 24, 2025
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@topperc topperc deleted the pr/atomic-rang-metadata branch April 24, 2025 19:14
@topperc topperc mentioned this pull request Apr 24, 2025
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@topperc @llvmbot @arsenm @s-barannikov