[SCCP] Remove masking operations #142736
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[SCCP] Remove masking operations #142736
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@llvm/pr-subscribers-function-specialization Author: Yingwei Zheng (dtcxzyw) ChangesCVP version: 2d5820c Full diff: https://github.com/llvm/llvm-project/pull/142736.diff 4 Files Affected:
diff --git a/llvm/lib/Transforms/Utils/SCCPSolver.cpp b/llvm/lib/Transforms/Utils/SCCPSolver.cpp
index 4535f86f9d68b..f9c075eaa602b 100644
--- a/llvm/lib/Transforms/Utils/SCCPSolver.cpp
+++ b/llvm/lib/Transforms/Utils/SCCPSolver.cpp
@@ -20,6 +20,7 @@
#include "llvm/Analysis/ValueLatticeUtils.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/InstVisitor.h"
+#include "llvm/IR/PatternMatch.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
@@ -30,6 +31,7 @@
#include <vector>
using namespace llvm;
+using namespace PatternMatch;
#define DEBUG_TYPE "sccp"
@@ -86,7 +88,7 @@ bool SCCPSolver::tryToReplaceWithConstant(Value *V) {
/// Try to use \p Inst's value range from \p Solver to infer the NUW flag.
static bool refineInstruction(SCCPSolver &Solver,
const SmallPtrSetImpl<Value *> &InsertedValues,
- Instruction &Inst) {
+ Instruction &Inst, Statistic &InstRemovedStat) {
bool Changed = false;
auto GetRange = [&Solver, &InsertedValues](Value *Op) {
if (auto *Const = dyn_cast<Constant>(Op))
@@ -99,6 +101,9 @@ static bool refineInstruction(SCCPSolver &Solver,
Op->getType(), /*UndefAllowed=*/false);
};
+ Value *X;
+ const APInt *RHSC;
+
if (isa<OverflowingBinaryOperator>(Inst)) {
if (Inst.hasNoSignedWrap() && Inst.hasNoUnsignedWrap())
return false;
@@ -157,6 +162,15 @@ static bool refineInstruction(SCCPSolver &Solver,
GEPNoWrapFlags::noUnsignedWrap());
Changed = true;
}
+ } else if (match(&Inst, m_And(m_Value(X), m_LowBitMask(RHSC)))) {
+ ConstantRange LRange = GetRange(Inst.getOperand(0));
+ if (!LRange.getUnsignedMax().ule(*RHSC))
+ return false;
+
+ Inst.replaceAllUsesWith(X);
+ Inst.eraseFromParent();
+ ++InstRemovedStat;
+ Changed = true;
}
return Changed;
@@ -249,7 +263,8 @@ bool SCCPSolver::simplifyInstsInBlock(BasicBlock &BB,
} else if (replaceSignedInst(*this, InsertedValues, Inst)) {
MadeChanges = true;
++InstReplacedStat;
- } else if (refineInstruction(*this, InsertedValues, Inst)) {
+ } else if (refineInstruction(*this, InsertedValues, Inst,
+ InstRemovedStat)) {
MadeChanges = true;
}
}
diff --git a/llvm/test/Transforms/SCCP/conditions-ranges-with-undef.ll b/llvm/test/Transforms/SCCP/conditions-ranges-with-undef.ll
index 8b4dea462757e..207f303b83460 100644
--- a/llvm/test/Transforms/SCCP/conditions-ranges-with-undef.ll
+++ b/llvm/test/Transforms/SCCP/conditions-ranges-with-undef.ll
@@ -46,8 +46,7 @@ define void @val_undef_range() {
; CHECK-NEXT: br i1 [[BC_1]], label [[TRUE:%.*]], label [[FALSE:%.*]]
; CHECK: true:
; CHECK-NEXT: call void @use(i1 false)
-; CHECK-NEXT: [[A_127:%.*]] = and i32 [[A]], 127
-; CHECK-NEXT: call void @use.i32(i32 [[A_127]])
+; CHECK-NEXT: call void @use.i32(i32 [[A]])
; CHECK-NEXT: ret void
; CHECK: false:
; CHECK-NEXT: ret void
@@ -82,8 +81,7 @@ define void @val_singlecrfromundef_range(i1 %cond) {
; CHECK-NEXT: br label [[TRUE:%.*]]
; CHECK: true:
; CHECK-NEXT: call void @use(i1 false)
-; CHECK-NEXT: [[P_127:%.*]] = and i32 10, 127
-; CHECK-NEXT: call void @use.i32(i32 [[P_127]])
+; CHECK-NEXT: call void @use.i32(i32 10)
; CHECK-NEXT: ret void
;
entry:
@@ -131,8 +129,7 @@ define void @val_undef_to_cr_to_overdef_range(i32 %a, i1 %cond) {
; CHECK-NEXT: br i1 [[BC_1]], label [[TRUE:%.*]], label [[FALSE:%.*]]
; CHECK: true:
; CHECK-NEXT: call void @use(i1 false)
-; CHECK-NEXT: [[P_127:%.*]] = and i32 [[P]], 127
-; CHECK-NEXT: call void @use.i32(i32 [[P_127]])
+; CHECK-NEXT: call void @use.i32(i32 [[P]])
; CHECK-NEXT: ret void
; CHECK: false:
; CHECK-NEXT: ret void
diff --git a/llvm/test/Transforms/SCCP/range-and.ll b/llvm/test/Transforms/SCCP/range-and.ll
index ef8758fcba9e2..f3452f45e1c02 100644
--- a/llvm/test/Transforms/SCCP/range-and.ll
+++ b/llvm/test/Transforms/SCCP/range-and.ll
@@ -1,4 +1,4 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --verbose
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S -passes=sccp %s | FileCheck %s
declare void @use(i1)
@@ -140,9 +140,8 @@ define i64 @constant_range_and_255_100(i1 %cond, i64 %a) {
; CHECK-NEXT: br label [[BB3]]
; CHECK: bb3:
; CHECK-NEXT: [[P:%.*]] = phi i64 [ [[R_1]], [[BB1]] ], [ [[R_2]], [[BB2]] ]
-; CHECK-NEXT: [[P_AND:%.*]] = and i64 [[P]], 255
; CHECK-NEXT: call void @use(i1 true)
-; CHECK-NEXT: ret i64 [[P_AND]]
+; CHECK-NEXT: ret i64 [[P]]
;
entry:
br i1 %cond, label %bb1, label %bb2
diff --git a/llvm/test/Transforms/SCCP/range-with-undef.ll b/llvm/test/Transforms/SCCP/range-with-undef.ll
index 9b8d415171140..774d95ceff428 100644
--- a/llvm/test/Transforms/SCCP/range-with-undef.ll
+++ b/llvm/test/Transforms/SCCP/range-with-undef.ll
@@ -12,8 +12,7 @@ define i8 @test_binop(i1 %cond, i8 %a) {
; CHECK-NEXT: [[A_EXT:%.*]] = zext i8 [[A]] to i16
; CHECK-NEXT: br label %[[JOIN]]
; CHECK: [[JOIN]]:
-; CHECK-NEXT: [[PHI:%.*]] = phi i16 [ undef, %[[ENTRY]] ], [ [[A_EXT]], %[[IF]] ]
-; CHECK-NEXT: [[AND:%.*]] = and i16 [[PHI]], -1
+; CHECK-NEXT: [[AND:%.*]] = phi i16 [ undef, %[[ENTRY]] ], [ [[A_EXT]], %[[IF]] ]
; CHECK-NEXT: [[TRUNC:%.*]] = trunc i16 [[AND]] to i8
; CHECK-NEXT: ret i8 [[TRUNC]]
;
|
|
@llvm/pr-subscribers-llvm-transforms Author: Yingwei Zheng (dtcxzyw) ChangesCVP version: 2d5820c Full diff: https://github.com/llvm/llvm-project/pull/142736.diff 4 Files Affected:
diff --git a/llvm/lib/Transforms/Utils/SCCPSolver.cpp b/llvm/lib/Transforms/Utils/SCCPSolver.cpp
index 4535f86f9d68b..f9c075eaa602b 100644
--- a/llvm/lib/Transforms/Utils/SCCPSolver.cpp
+++ b/llvm/lib/Transforms/Utils/SCCPSolver.cpp
@@ -20,6 +20,7 @@
#include "llvm/Analysis/ValueLatticeUtils.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/InstVisitor.h"
+#include "llvm/IR/PatternMatch.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
@@ -30,6 +31,7 @@
#include <vector>
using namespace llvm;
+using namespace PatternMatch;
#define DEBUG_TYPE "sccp"
@@ -86,7 +88,7 @@ bool SCCPSolver::tryToReplaceWithConstant(Value *V) {
/// Try to use \p Inst's value range from \p Solver to infer the NUW flag.
static bool refineInstruction(SCCPSolver &Solver,
const SmallPtrSetImpl<Value *> &InsertedValues,
- Instruction &Inst) {
+ Instruction &Inst, Statistic &InstRemovedStat) {
bool Changed = false;
auto GetRange = [&Solver, &InsertedValues](Value *Op) {
if (auto *Const = dyn_cast<Constant>(Op))
@@ -99,6 +101,9 @@ static bool refineInstruction(SCCPSolver &Solver,
Op->getType(), /*UndefAllowed=*/false);
};
+ Value *X;
+ const APInt *RHSC;
+
if (isa<OverflowingBinaryOperator>(Inst)) {
if (Inst.hasNoSignedWrap() && Inst.hasNoUnsignedWrap())
return false;
@@ -157,6 +162,15 @@ static bool refineInstruction(SCCPSolver &Solver,
GEPNoWrapFlags::noUnsignedWrap());
Changed = true;
}
+ } else if (match(&Inst, m_And(m_Value(X), m_LowBitMask(RHSC)))) {
+ ConstantRange LRange = GetRange(Inst.getOperand(0));
+ if (!LRange.getUnsignedMax().ule(*RHSC))
+ return false;
+
+ Inst.replaceAllUsesWith(X);
+ Inst.eraseFromParent();
+ ++InstRemovedStat;
+ Changed = true;
}
return Changed;
@@ -249,7 +263,8 @@ bool SCCPSolver::simplifyInstsInBlock(BasicBlock &BB,
} else if (replaceSignedInst(*this, InsertedValues, Inst)) {
MadeChanges = true;
++InstReplacedStat;
- } else if (refineInstruction(*this, InsertedValues, Inst)) {
+ } else if (refineInstruction(*this, InsertedValues, Inst,
+ InstRemovedStat)) {
MadeChanges = true;
}
}
diff --git a/llvm/test/Transforms/SCCP/conditions-ranges-with-undef.ll b/llvm/test/Transforms/SCCP/conditions-ranges-with-undef.ll
index 8b4dea462757e..207f303b83460 100644
--- a/llvm/test/Transforms/SCCP/conditions-ranges-with-undef.ll
+++ b/llvm/test/Transforms/SCCP/conditions-ranges-with-undef.ll
@@ -46,8 +46,7 @@ define void @val_undef_range() {
; CHECK-NEXT: br i1 [[BC_1]], label [[TRUE:%.*]], label [[FALSE:%.*]]
; CHECK: true:
; CHECK-NEXT: call void @use(i1 false)
-; CHECK-NEXT: [[A_127:%.*]] = and i32 [[A]], 127
-; CHECK-NEXT: call void @use.i32(i32 [[A_127]])
+; CHECK-NEXT: call void @use.i32(i32 [[A]])
; CHECK-NEXT: ret void
; CHECK: false:
; CHECK-NEXT: ret void
@@ -82,8 +81,7 @@ define void @val_singlecrfromundef_range(i1 %cond) {
; CHECK-NEXT: br label [[TRUE:%.*]]
; CHECK: true:
; CHECK-NEXT: call void @use(i1 false)
-; CHECK-NEXT: [[P_127:%.*]] = and i32 10, 127
-; CHECK-NEXT: call void @use.i32(i32 [[P_127]])
+; CHECK-NEXT: call void @use.i32(i32 10)
; CHECK-NEXT: ret void
;
entry:
@@ -131,8 +129,7 @@ define void @val_undef_to_cr_to_overdef_range(i32 %a, i1 %cond) {
; CHECK-NEXT: br i1 [[BC_1]], label [[TRUE:%.*]], label [[FALSE:%.*]]
; CHECK: true:
; CHECK-NEXT: call void @use(i1 false)
-; CHECK-NEXT: [[P_127:%.*]] = and i32 [[P]], 127
-; CHECK-NEXT: call void @use.i32(i32 [[P_127]])
+; CHECK-NEXT: call void @use.i32(i32 [[P]])
; CHECK-NEXT: ret void
; CHECK: false:
; CHECK-NEXT: ret void
diff --git a/llvm/test/Transforms/SCCP/range-and.ll b/llvm/test/Transforms/SCCP/range-and.ll
index ef8758fcba9e2..f3452f45e1c02 100644
--- a/llvm/test/Transforms/SCCP/range-and.ll
+++ b/llvm/test/Transforms/SCCP/range-and.ll
@@ -1,4 +1,4 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --verbose
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S -passes=sccp %s | FileCheck %s
declare void @use(i1)
@@ -140,9 +140,8 @@ define i64 @constant_range_and_255_100(i1 %cond, i64 %a) {
; CHECK-NEXT: br label [[BB3]]
; CHECK: bb3:
; CHECK-NEXT: [[P:%.*]] = phi i64 [ [[R_1]], [[BB1]] ], [ [[R_2]], [[BB2]] ]
-; CHECK-NEXT: [[P_AND:%.*]] = and i64 [[P]], 255
; CHECK-NEXT: call void @use(i1 true)
-; CHECK-NEXT: ret i64 [[P_AND]]
+; CHECK-NEXT: ret i64 [[P]]
;
entry:
br i1 %cond, label %bb1, label %bb2
diff --git a/llvm/test/Transforms/SCCP/range-with-undef.ll b/llvm/test/Transforms/SCCP/range-with-undef.ll
index 9b8d415171140..774d95ceff428 100644
--- a/llvm/test/Transforms/SCCP/range-with-undef.ll
+++ b/llvm/test/Transforms/SCCP/range-with-undef.ll
@@ -12,8 +12,7 @@ define i8 @test_binop(i1 %cond, i8 %a) {
; CHECK-NEXT: [[A_EXT:%.*]] = zext i8 [[A]] to i16
; CHECK-NEXT: br label %[[JOIN]]
; CHECK: [[JOIN]]:
-; CHECK-NEXT: [[PHI:%.*]] = phi i16 [ undef, %[[ENTRY]] ], [ [[A_EXT]], %[[IF]] ]
-; CHECK-NEXT: [[AND:%.*]] = and i16 [[PHI]], -1
+; CHECK-NEXT: [[AND:%.*]] = phi i16 [ undef, %[[ENTRY]] ], [ [[A_EXT]], %[[IF]] ]
; CHECK-NEXT: [[TRUNC:%.*]] = trunc i16 [[AND]] to i8
; CHECK-NEXT: ret i8 [[TRUNC]]
;
|
nikic
reviewed
Jun 4, 2025
| @@ -157,6 +162,15 @@ static bool refineInstruction(SCCPSolver &Solver, | |||
| GEPNoWrapFlags::noUnsignedWrap()); | |||
| Changed = true; | |||
| } | |||
| } else if (match(&Inst, m_And(m_Value(X), m_LowBitMask(RHSC)))) { | |||
There was a problem hiding this comment.
Could try generalizing this away from LowBitMask in a followup. For CVP this reduces compile-time, but for IPSCCP it shouldn't matter.
You can test this locally with the following command:git diff -U0 --pickaxe-regex -S '([^a-zA-Z0-9#_-]undef[^a-zA-Z0-9_-]|UndefValue::get)' 'HEAD~1' HEAD llvm/lib/Transforms/Utils/SCCPSolver.cpp llvm/test/Transforms/SCCP/conditions-ranges-with-undef.ll llvm/test/Transforms/SCCP/range-and.ll llvm/test/Transforms/SCCP/range-with-undef.llThe following files introduce new uses of undef:
Undef is now deprecated and should only be used in the rare cases where no replacement is possible. For example, a load of uninitialized memory yields In tests, avoid using For example, this is considered a bad practice: define void @fn() {
...
br i1 undef, ...
}Please use the following instead: define void @fn(i1 %cond) {
...
br i1 %cond, ...
}Please refer to the Undefined Behavior Manual for more information. |
fhahn
reviewed
Jun 4, 2025
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/11/builds/16585 Here is the relevant piece of the build log for the reference |
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/66/builds/14913 Here is the relevant piece of the build log for the reference |
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CVP version: 2d5820c
Compile-time impact: https://llvm-compile-time-tracker.com/compare.php?from=3ec0c5c7fef03985b43432c6b914c289d8a5435e&to=92b4df90695dd37defdabf8a30f0b0322b648a00&stat=instructions:u