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[TailDuplicator] Determine if computed gotos using blockaddress #132536

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[TailDuplicator] Determine if computed gotos using blockaddress #132536

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@dianqk dianqk commented Mar 22, 2025 •
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Using blockaddress should be more reliable than determining if an operand comes from a jump table index.

Alternative: Add the MachineInstr::MIFlag::ComputedGoto flag when lowering indirectbr. But I don't think this approach is suitable to backport.

I can confirm that Ajla and CPython are both fine.

@dianqk dianqk requested review from nikic, fhahn and alexfh March 22, 2025 10:07
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llvmbot commented Mar 22, 2025

@llvm/pr-subscribers-backend-x86

Author: dianqk (dianqk)

Changes

Using blockaddress should be more reliable than determining if an operand comes from a jump table index.

Alternative: Add the MachineInstr::MIFlag::ComputedGoto flag when lowering indirectbr. But I don't think this approach is suitable to backport.

Full diff: https://github.com/llvm/llvm-project/pull/132536.diff

3 Files Affected:

  • (modified) llvm/include/llvm/CodeGen/MachineInstr.h (+4-3)
  • (modified) llvm/lib/CodeGen/MachineInstr.cpp (+6)
  • (modified) llvm/test/CodeGen/X86/tail-dup-computed-goto.mir (+164-10)
diff --git a/llvm/include/llvm/CodeGen/MachineInstr.h b/llvm/include/llvm/CodeGen/MachineInstr.h
index b26cabe801ee8..6651431c9afad 100644
--- a/llvm/include/llvm/CodeGen/MachineInstr.h
+++ b/llvm/include/llvm/CodeGen/MachineInstr.h
@@ -997,9 +997,7 @@ class MachineInstr
   bool isIndirectBranch(QueryType Type = AnyInBundle,
                         bool IncludeJumpTable = true) const {
     return hasProperty(MCID::IndirectBranch, Type) &&
-           (IncludeJumpTable || !llvm::any_of(operands(), [](const auto &Op) {
-              return Op.isJTI();
-            }));
+           (IncludeJumpTable || jumpToIRBlockAddressTaken());
   }
 
   bool isComputedGoto(QueryType Type = AnyInBundle) const {
@@ -2088,6 +2086,9 @@ class MachineInstr
                     MCSymbol *PreInstrSymbol, MCSymbol *PostInstrSymbol,
                     MDNode *HeapAllocMarker, MDNode *PCSections,
                     uint32_t CFIType, MDNode *MMRAs);
+
+  /// Returns true if all successors are IRBlockAddressTaken.
+  bool jumpToIRBlockAddressTaken() const;
 };
 
 /// Special DenseMapInfo traits to compare MachineInstr* by *value* of the
diff --git a/llvm/lib/CodeGen/MachineInstr.cpp b/llvm/lib/CodeGen/MachineInstr.cpp
index 471666568e79a..3c2d7d2b9ddbd 100644
--- a/llvm/lib/CodeGen/MachineInstr.cpp
+++ b/llvm/lib/CodeGen/MachineInstr.cpp
@@ -359,6 +359,12 @@ void MachineInstr::setExtraInfo(MachineFunction &MF,
     Info.set<EIIK_MMO>(MMOs[0]);
 }
 
+bool MachineInstr::jumpToIRBlockAddressTaken() const {
+  return llvm::all_of(getParent()->successors(), [](const auto *Succ) {
+    return Succ->isIRBlockAddressTaken();
+  });
+}
+
 void MachineInstr::dropMemRefs(MachineFunction &MF) {
   if (memoperands_empty())
     return;
diff --git a/llvm/test/CodeGen/X86/tail-dup-computed-goto.mir b/llvm/test/CodeGen/X86/tail-dup-computed-goto.mir
index a472dc67d8d51..4d50094d606b9 100644
--- a/llvm/test/CodeGen/X86/tail-dup-computed-goto.mir
+++ b/llvm/test/CodeGen/X86/tail-dup-computed-goto.mir
@@ -8,9 +8,21 @@
   declare i64 @f3()
   declare i64 @f4()
   declare i64 @f5()
-  @computed_goto.dispatch = external global [5 x ptr]
-  define void @computed_goto() { ret void }
+  @computed_goto.dispatch = constant [5 x ptr] [ptr null, ptr blockaddress(@computed_goto, %bb1), ptr blockaddress(@computed_goto, %bb2), ptr blockaddress(@computed_goto, %bb3), ptr blockaddress(@computed_goto, %bb4)]
+  define void @computed_goto() {
+    start:
+      ret void
+    bb1:
+      ret void
+    bb2:
+      ret void
+    bb3:
+      ret void
+    bb4:
+      ret void
+  }
   define void @jump_table() { ret void }
+  define void @jump_table_pic() { ret void }
 ...
 ---
 name:            computed_goto
@@ -28,7 +40,7 @@ body:             |
   ; CHECK-NEXT:   [[COPY2:%[0-9]+]]:gr64_nosp = COPY [[COPY1]]
   ; CHECK-NEXT:   JMP64m $noreg, 8, [[COPY1]], @computed_goto.dispatch, $noreg
   ; CHECK-NEXT: {{  $}}
-  ; CHECK-NEXT: bb.1:
+  ; CHECK-NEXT: bb.1.bb1 (ir-block-address-taken %ir-block.bb1):
   ; CHECK-NEXT:   successors: %bb.1(0x20000000), %bb.2(0x20000000), %bb.3(0x20000000), %bb.4(0x20000000)
   ; CHECK-NEXT: {{  $}}
   ; CHECK-NEXT:   ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
@@ -39,7 +51,7 @@ body:             |
   ; CHECK-NEXT:   [[COPY5:%[0-9]+]]:gr64_nosp = COPY [[COPY4]]
   ; CHECK-NEXT:   JMP64m $noreg, 8, [[COPY4]], @computed_goto.dispatch, $noreg
   ; CHECK-NEXT: {{  $}}
-  ; CHECK-NEXT: bb.2:
+  ; CHECK-NEXT: bb.2.bb2 (ir-block-address-taken %ir-block.bb2):
   ; CHECK-NEXT:   successors: %bb.1(0x20000000), %bb.2(0x20000000), %bb.3(0x20000000), %bb.4(0x20000000)
   ; CHECK-NEXT: {{  $}}
   ; CHECK-NEXT:   ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
@@ -50,7 +62,7 @@ body:             |
   ; CHECK-NEXT:   [[COPY8:%[0-9]+]]:gr64_nosp = COPY [[COPY7]]
   ; CHECK-NEXT:   JMP64m $noreg, 8, [[COPY7]], @computed_goto.dispatch, $noreg
   ; CHECK-NEXT: {{  $}}
-  ; CHECK-NEXT: bb.3:
+  ; CHECK-NEXT: bb.3.bb3 (ir-block-address-taken %ir-block.bb3):
   ; CHECK-NEXT:   successors: %bb.1(0x20000000), %bb.2(0x20000000), %bb.3(0x20000000), %bb.4(0x20000000)
   ; CHECK-NEXT: {{  $}}
   ; CHECK-NEXT:   ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
@@ -61,7 +73,7 @@ body:             |
   ; CHECK-NEXT:   [[COPY11:%[0-9]+]]:gr64_nosp = COPY [[COPY10]]
   ; CHECK-NEXT:   JMP64m $noreg, 8, [[COPY10]], @computed_goto.dispatch, $noreg
   ; CHECK-NEXT: {{  $}}
-  ; CHECK-NEXT: bb.4:
+  ; CHECK-NEXT: bb.4.bb4 (ir-block-address-taken %ir-block.bb4):
   ; CHECK-NEXT:   successors: %bb.1(0x20000000), %bb.2(0x20000000), %bb.3(0x20000000), %bb.4(0x20000000)
   ; CHECK-NEXT: {{  $}}
   ; CHECK-NEXT:   ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
@@ -79,7 +91,7 @@ body:             |
     %0:gr64 = COPY %6
     JMP_1 %bb.5
 
-  bb.1:
+  bb.1.bb1 (ir-block-address-taken %ir-block.bb1):
     ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
     CALL64pcrel32 target-flags(x86-plt) @f1, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $rax
     ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
@@ -87,7 +99,7 @@ body:             |
     %1:gr64 = COPY %10
     JMP_1 %bb.5
 
-  bb.2:
+  bb.2.bb2 (ir-block-address-taken %ir-block.bb2):
     ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
     CALL64pcrel32 target-flags(x86-plt) @f2, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $rax
     ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
@@ -95,7 +107,7 @@ body:             |
     %2:gr64 = COPY %9
     JMP_1 %bb.5
 
-  bb.3:
+  bb.3.bb3 (ir-block-address-taken %ir-block.bb3):
     ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
     CALL64pcrel32 target-flags(x86-plt) @f3, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $rax
     ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
@@ -103,7 +115,7 @@ body:             |
     %3:gr64 = COPY %8
     JMP_1 %bb.5
 
-  bb.4:
+  bb.4.bb4 (ir-block-address-taken %ir-block.bb4):
     ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
     CALL64pcrel32 target-flags(x86-plt) @f4, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $rax
     ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
@@ -253,3 +265,145 @@ body:             |
   bb.7:
 
 ...
+---
+name:            jump_table_pic
+tracksRegLiveness: true
+jumpTable:
+  kind:            block-address
+  entries:
+    - id:              0
+      blocks:          [ '%bb.2', '%bb.3', '%bb.4', '%bb.5', '%bb.6' ]
+body:             |
+  ; CHECK-LABEL: name: jump_table_pic
+  ; CHECK: bb.0:
+  ; CHECK-NEXT:   successors: %bb.1(0x80000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+  ; CHECK-NEXT:   CALL64pcrel32 target-flags(x86-plt) @f0, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $rax
+  ; CHECK-NEXT:   ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+  ; CHECK-NEXT:   [[COPY:%[0-9]+]]:gr64 = COPY $rax
+  ; CHECK-NEXT:   [[COPY1:%[0-9]+]]:gr64 = COPY [[COPY]]
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.1:
+  ; CHECK-NEXT:   successors: %bb.3(0x1999999a), %bb.4(0x1999999a), %bb.5(0x1999999a), %bb.6(0x1999999a), %bb.7(0x1999999a)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[PHI:%[0-9]+]]:gr64 = PHI [[COPY1]], %bb.0, %3, %bb.7, %4, %bb.6, %5, %bb.5, %6, %bb.4, %7, %bb.3
+  ; CHECK-NEXT:   [[DEC64r:%[0-9]+]]:gr64_nosp = DEC64r [[PHI]], implicit-def dead $eflags
+  ; CHECK-NEXT:   [[LEA64r:%[0-9]+]]:gr64 = LEA64r $rip, 1, $noreg, %jump-table.0, $noreg
+  ; CHECK-NEXT:   [[MOVSX64rm32_:%[0-9]+]]:gr64 = MOVSX64rm32 [[DEC64r]], 4, [[DEC64r]], 0, $noreg :: (load (s32) from jump-table)
+  ; CHECK-NEXT:   [[ADD64rr:%[0-9]+]]:gr64 = ADD64rr [[LEA64r]], [[MOVSX64rm32_]], implicit-def dead $eflags
+  ; CHECK-NEXT:   JMP64r [[ADD64rr]]
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.3:
+  ; CHECK-NEXT:   successors: %bb.1(0x80000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+  ; CHECK-NEXT:   CALL64pcrel32 target-flags(x86-plt) @f1, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $rax
+  ; CHECK-NEXT:   ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+  ; CHECK-NEXT:   [[COPY2:%[0-9]+]]:gr64 = COPY $rax
+  ; CHECK-NEXT:   [[COPY3:%[0-9]+]]:gr64 = COPY [[COPY2]]
+  ; CHECK-NEXT:   JMP_1 %bb.1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.4:
+  ; CHECK-NEXT:   successors: %bb.1(0x80000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+  ; CHECK-NEXT:   CALL64pcrel32 target-flags(x86-plt) @f2, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $rax
+  ; CHECK-NEXT:   ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+  ; CHECK-NEXT:   [[COPY4:%[0-9]+]]:gr64 = COPY $rax
+  ; CHECK-NEXT:   [[COPY5:%[0-9]+]]:gr64 = COPY [[COPY4]]
+  ; CHECK-NEXT:   JMP_1 %bb.1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.5:
+  ; CHECK-NEXT:   successors: %bb.1(0x80000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+  ; CHECK-NEXT:   CALL64pcrel32 target-flags(x86-plt) @f3, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $rax
+  ; CHECK-NEXT:   ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+  ; CHECK-NEXT:   [[COPY6:%[0-9]+]]:gr64 = COPY $rax
+  ; CHECK-NEXT:   [[COPY7:%[0-9]+]]:gr64 = COPY [[COPY6]]
+  ; CHECK-NEXT:   JMP_1 %bb.1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.6:
+  ; CHECK-NEXT:   successors: %bb.1(0x80000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+  ; CHECK-NEXT:   CALL64pcrel32 target-flags(x86-plt) @f4, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $rax
+  ; CHECK-NEXT:   ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+  ; CHECK-NEXT:   [[COPY8:%[0-9]+]]:gr64 = COPY $rax
+  ; CHECK-NEXT:   [[COPY9:%[0-9]+]]:gr64 = COPY [[COPY8]]
+  ; CHECK-NEXT:   JMP_1 %bb.1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.7:
+  ; CHECK-NEXT:   successors: %bb.1(0x80000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+  ; CHECK-NEXT:   CALL64pcrel32 target-flags(x86-plt) @f5, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $rax
+  ; CHECK-NEXT:   ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+  ; CHECK-NEXT:   [[COPY10:%[0-9]+]]:gr64 = COPY $rax
+  ; CHECK-NEXT:   [[COPY11:%[0-9]+]]:gr64 = COPY [[COPY10]]
+  ; CHECK-NEXT:   JMP_1 %bb.1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.8:
+  bb.0:
+    ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+    CALL64pcrel32 target-flags(x86-plt) @f0, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $rax
+    ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+    %7:gr64 = COPY $rax
+    %0:gr64 = COPY %7
+
+  bb.1:
+    %1:gr64 = PHI %0, %bb.0, %6, %bb.6, %5, %bb.5, %4, %bb.4, %3, %bb.3, %2, %bb.2
+    %8:gr64_nosp = DEC64r %1, implicit-def dead $eflags
+
+  bb.8:
+    successors: %bb.2(0x1999999a), %bb.3(0x1999999a), %bb.4(0x1999999a), %bb.5(0x1999999a), %bb.6(0x1999999a)
+
+    %14:gr64 = LEA64r $rip, 1, $noreg, %jump-table.0, $noreg
+    %15:gr64 = MOVSX64rm32 %8, 4, %8, 0, $noreg :: (load (s32) from jump-table)
+    %16:gr64 = ADD64rr %14, killed %15, implicit-def dead $eflags
+    JMP64r killed %16
+
+  bb.2:
+    ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+    CALL64pcrel32 target-flags(x86-plt) @f1, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $rax
+    ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+    %13:gr64 = COPY $rax
+    %2:gr64 = COPY %13
+    JMP_1 %bb.1
+
+  bb.3:
+    ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+    CALL64pcrel32 target-flags(x86-plt) @f2, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $rax
+    ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+    %12:gr64 = COPY $rax
+    %3:gr64 = COPY %12
+    JMP_1 %bb.1
+
+  bb.4:
+    ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+    CALL64pcrel32 target-flags(x86-plt) @f3, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $rax
+    ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+    %11:gr64 = COPY $rax
+    %4:gr64 = COPY %11
+    JMP_1 %bb.1
+
+  bb.5:
+    ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+    CALL64pcrel32 target-flags(x86-plt) @f4, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $rax
+    ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+    %10:gr64 = COPY $rax
+    %5:gr64 = COPY %10
+    JMP_1 %bb.1
+
+  bb.6:
+    ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+    CALL64pcrel32 target-flags(x86-plt) @f5, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $rax
+    ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+    %9:gr64 = COPY $rax
+    %6:gr64 = COPY %9
+    JMP_1 %bb.1
+
+  bb.7:
+
+...

This was referenced Mar 22, 2025
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@nikic nikic requested a review from arsenm March 22, 2025 15:12
alexfh
alexfh approved these changes Mar 24, 2025
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I verified that this fixes the problems we've found so far, but I can't say anything about the correctness or other aspects of this approach.

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alexfh commented Mar 24, 2025

Please ensure the buildkite errors are not related to this PR.

@dianqk dianqk force-pushed the computed-goto-blockaddress branch from 10353d6 to 4ed0b5f Compare March 24, 2025 12:58
arsenm
arsenm requested changes Mar 25, 2025
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isIndirectBranch is a low level instruction query. I expect it to inform of properties that directly apply to the instruction itself, and it is inappropriate for it to inspect the CFG. This code should be moved somewhere else

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dianqk commented Mar 25, 2025

isIndirectBranch is a low level instruction query. I expect it to inform of properties that directly apply to the instruction itself, and it is inappropriate for it to inspect the CFG. This code should be moved somewhere else

I moved this to MachineBasicBlock.

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@arsenm arsenm arsenm requested changes

@alexfh alexfh alexfh approved these changes

@nikic nikic Awaiting requested review from nikic

@fhahn fhahn Awaiting requested review from fhahn

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