[llvm] d18ca43 - [ConstraintElimination] Add support for UCMP/SCMP intrinsics (#97974)
via llvm-commits
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Wed Jul 10 13:00:01 PDT 2024
Author: Poseydon42
Date: 2024-07-10T21:59:59+02:00
New Revision: d18ca43edc6fed920db86a99ed9f7e3bcafc99d2
URL: https://github.com/llvm/llvm-project/commit/d18ca43edc6fed920db86a99ed9f7e3bcafc99d2
DIFF: https://github.com/llvm/llvm-project/commit/d18ca43edc6fed920db86a99ed9f7e3bcafc99d2.diff
LOG: [ConstraintElimination] Add support for UCMP/SCMP intrinsics (#97974)
This adds checks to fold calls to `ucmp`/`scmp` where a comparative
relationship between the arguments can be established.
Added:
llvm/test/Transforms/ConstraintElimination/uscmp.ll
Modified:
llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
index 52d9969426105..c31173879af1e 100644
--- a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
@@ -1087,6 +1087,8 @@ void State::addInfoFor(BasicBlock &BB) {
}
// Enqueue ssub_with_overflow for simplification.
case Intrinsic::ssub_with_overflow:
+ case Intrinsic::ucmp:
+ case Intrinsic::scmp:
WorkList.push_back(
FactOrCheck::getCheck(DT.getNode(&BB), cast<CallInst>(&I)));
break;
@@ -1448,6 +1450,28 @@ static bool checkAndReplaceMinMax(MinMaxIntrinsic *MinMax, ConstraintInfo &Info,
return false;
}
+static bool checkAndReplaceCmp(CmpIntrinsic *I, ConstraintInfo &Info,
+ SmallVectorImpl<Instruction *> &ToRemove) {
+ Value *LHS = I->getOperand(0);
+ Value *RHS = I->getOperand(1);
+ if (checkCondition(I->getGTPredicate(), LHS, RHS, I, Info).value_or(false)) {
+ I->replaceAllUsesWith(ConstantInt::get(I->getType(), 1));
+ ToRemove.push_back(I);
+ return true;
+ }
+ if (checkCondition(I->getLTPredicate(), LHS, RHS, I, Info).value_or(false)) {
+ I->replaceAllUsesWith(ConstantInt::getSigned(I->getType(), -1));
+ ToRemove.push_back(I);
+ return true;
+ }
+ if (checkCondition(ICmpInst::ICMP_EQ, LHS, RHS, I, Info)) {
+ I->replaceAllUsesWith(ConstantInt::get(I->getType(), 0));
+ ToRemove.push_back(I);
+ return true;
+ }
+ return false;
+}
+
static void
removeEntryFromStack(const StackEntry &E, ConstraintInfo &Info,
Module *ReproducerModule,
@@ -1750,6 +1774,8 @@ static bool eliminateConstraints(Function &F, DominatorTree &DT, LoopInfo &LI,
Changed |= Simplified;
} else if (auto *MinMax = dyn_cast<MinMaxIntrinsic>(Inst)) {
Changed |= checkAndReplaceMinMax(MinMax, Info, ToRemove);
+ } else if (auto *CmpIntr = dyn_cast<CmpIntrinsic>(Inst)) {
+ Changed |= checkAndReplaceCmp(CmpIntr, Info, ToRemove);
}
continue;
}
diff --git a/llvm/test/Transforms/ConstraintElimination/uscmp.ll b/llvm/test/Transforms/ConstraintElimination/uscmp.ll
new file mode 100644
index 0000000000000..63ac050f2c3c5
--- /dev/null
+++ b/llvm/test/Transforms/ConstraintElimination/uscmp.ll
@@ -0,0 +1,149 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -passes=constraint-elimination -S %s | FileCheck %s
+
+define i8 @scmp_1(i32 %x, i32 %y) {
+; CHECK-LABEL: @scmp_1(
+; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: br i1 [[COND]], label [[TRUE:%.*]], label [[FALSE:%.*]]
+; CHECK: true:
+; CHECK-NEXT: ret i8 1
+; CHECK: false:
+; CHECK-NEXT: ret i8 20
+;
+ %cond = icmp sgt i32 %x, %y
+ br i1 %cond, label %true, label %false
+true:
+ %r = call i8 @llvm.scmp(i32 %x, i32 %y)
+ ret i8 %r
+false:
+ ret i8 20
+}
+
+define i8 @ucmp_1(i32 %x, i32 %y) {
+; CHECK-LABEL: @ucmp_1(
+; CHECK-NEXT: [[COND:%.*]] = icmp ult i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: br i1 [[COND]], label [[TRUE:%.*]], label [[FALSE:%.*]]
+; CHECK: true:
+; CHECK-NEXT: ret i8 -1
+; CHECK: false:
+; CHECK-NEXT: ret i8 20
+;
+ %cond = icmp ult i32 %x, %y
+ br i1 %cond, label %true, label %false
+true:
+ %r = call i8 @llvm.ucmp(i32 %x, i32 %y)
+ ret i8 %r
+false:
+ ret i8 20
+}
+
+define i8 @scmp_2(i32 %x, i32 %y) {
+; CHECK-LABEL: @scmp_2(
+; CHECK-NEXT: [[COND:%.*]] = icmp sge i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: br i1 [[COND]], label [[TRUE:%.*]], label [[FALSE:%.*]]
+; CHECK: true:
+; CHECK-NEXT: ret i8 20
+; CHECK: false:
+; CHECK-NEXT: ret i8 -1
+;
+ %cond = icmp sge i32 %x, %y
+ br i1 %cond, label %true, label %false
+true:
+ ret i8 20
+false:
+ %r = call i8 @llvm.scmp(i32 %x, i32 %y)
+ ret i8 %r
+}
+
+define i8 @ucmp_2(i32 %x, i32 %y) {
+; CHECK-LABEL: @ucmp_2(
+; CHECK-NEXT: [[COND:%.*]] = icmp ule i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: br i1 [[COND]], label [[TRUE:%.*]], label [[FALSE:%.*]]
+; CHECK: true:
+; CHECK-NEXT: ret i8 20
+; CHECK: false:
+; CHECK-NEXT: ret i8 1
+;
+ %cond = icmp ule i32 %x, %y
+ br i1 %cond, label %true, label %false
+true:
+ ret i8 20
+false:
+ %r = call i8 @llvm.ucmp(i32 %x, i32 %y)
+ ret i8 %r
+}
+
+define i8 @scmp_3(i32 %x, i32 %y) {
+; CHECK-LABEL: @scmp_3(
+; CHECK-NEXT: [[COND:%.*]] = icmp eq i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: br i1 [[COND]], label [[TRUE:%.*]], label [[FALSE:%.*]]
+; CHECK: true:
+; CHECK-NEXT: ret i8 0
+; CHECK: false:
+; CHECK-NEXT: ret i8 20
+;
+ %cond = icmp eq i32 %x, %y
+ br i1 %cond, label %true, label %false
+true:
+ %r = call i8 @llvm.scmp(i32 %x, i32 %y)
+ ret i8 %r
+false:
+ ret i8 20
+}
+
+define i8 @ucmp_3(i32 %x, i32 %y) {
+; CHECK-LABEL: @ucmp_3(
+; CHECK-NEXT: [[COND:%.*]] = icmp eq i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: br i1 [[COND]], label [[TRUE:%.*]], label [[FALSE:%.*]]
+; CHECK: true:
+; CHECK-NEXT: ret i8 0
+; CHECK: false:
+; CHECK-NEXT: ret i8 20
+;
+ %cond = icmp eq i32 %x, %y
+ br i1 %cond, label %true, label %false
+true:
+ %r = call i8 @llvm.ucmp(i32 %x, i32 %y)
+ ret i8 %r
+false:
+ ret i8 20
+}
+
+; Negative test: signedness mismatch
+define i8 @scmp_4(i32 %x, i32 %y) {
+; CHECK-LABEL: @scmp_4(
+; CHECK-NEXT: [[COND:%.*]] = icmp ugt i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: br i1 [[COND]], label [[TRUE:%.*]], label [[FALSE:%.*]]
+; CHECK: true:
+; CHECK-NEXT: ret i8 20
+; CHECK: false:
+; CHECK-NEXT: [[R:%.*]] = call i8 @llvm.scmp.i8.i32(i32 [[X]], i32 [[Y]])
+; CHECK-NEXT: ret i8 [[R]]
+;
+ %cond = icmp ugt i32 %x, %y
+ br i1 %cond, label %true, label %false
+true:
+ ret i8 20
+false:
+ %r = call i8 @llvm.scmp(i32 %x, i32 %y)
+ ret i8 %r
+}
+
+define i8 @ucmp_4(i32 %x, i32 %y) {
+; CHECK-LABEL: @ucmp_4(
+; CHECK-NEXT: [[COND:%.*]] = icmp slt i32 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: br i1 [[COND]], label [[TRUE:%.*]], label [[FALSE:%.*]]
+; CHECK: true:
+; CHECK-NEXT: ret i8 20
+; CHECK: false:
+; CHECK-NEXT: [[R:%.*]] = call i8 @llvm.ucmp.i8.i32(i32 [[X]], i32 [[Y]])
+; CHECK-NEXT: ret i8 [[R]]
+;
+ %cond = icmp slt i32 %x, %y
+ br i1 %cond, label %true, label %false
+true:
+ ret i8 20
+false:
+ %r = call i8 @llvm.ucmp(i32 %x, i32 %y)
+ ret i8 %r
+}
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