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release/18.x: [CGP] Drop poison-generating flags after hoisting (#90382) #90437

Closed llvmbot closed 2 weeks ago

llvmbot commented 2 weeks ago

Backport ab12bba0aad800c1805eca2ea937da958c1854c8

Requested by: @dtcxzyw

llvmbot commented 2 weeks ago

@nikic What do you think about merging this PR to the release branch?

llvmbot commented 2 weeks ago

@llvm/pr-subscribers-llvm-transforms

Author: None (llvmbot)

Changes Backport ab12bba0aad800c1805eca2ea937da958c1854c8 Requested by: @dtcxzyw --- Full diff: https://github.com/llvm/llvm-project/pull/90437.diff 3 Files Affected: - (modified) llvm/lib/CodeGen/CodeGenPrepare.cpp (+2) - (modified) llvm/test/Transforms/CodeGenPrepare/ARM/branch-on-zero.ll (+23) - (added) llvm/test/Transforms/CodeGenPrepare/RISCV/convert-to-eqz.ll (+80) ``````````diff diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp index 8ee1f19e083e4e..1cca56fc19cfd8 100644 --- a/llvm/lib/CodeGen/CodeGenPrepare.cpp +++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp @@ -8154,6 +8154,7 @@ static bool optimizeBranch(BranchInst *Branch, const TargetLowering &TLI, IRBuilder<> Builder(Branch); if (UI->getParent() != Branch->getParent()) UI->moveBefore(Branch); + UI->dropPoisonGeneratingFlags(); Value *NewCmp = Builder.CreateCmp(ICmpInst::ICMP_EQ, UI, ConstantInt::get(UI->getType(), 0)); LLVM_DEBUG(dbgs() << "Converting " << *Cmp << "\n"); @@ -8167,6 +8168,7 @@ static bool optimizeBranch(BranchInst *Branch, const TargetLowering &TLI, IRBuilder<> Builder(Branch); if (UI->getParent() != Branch->getParent()) UI->moveBefore(Branch); + UI->dropPoisonGeneratingFlags(); Value *NewCmp = Builder.CreateCmp(Cmp->getPredicate(), UI, ConstantInt::get(UI->getType(), 0)); LLVM_DEBUG(dbgs() << "Converting " << *Cmp << "\n"); diff --git a/llvm/test/Transforms/CodeGenPrepare/ARM/branch-on-zero.ll b/llvm/test/Transforms/CodeGenPrepare/ARM/branch-on-zero.ll index ff5cef7e781fe6..25dfb3c53a077b 100644 --- a/llvm/test/Transforms/CodeGenPrepare/ARM/branch-on-zero.ll +++ b/llvm/test/Transforms/CodeGenPrepare/ARM/branch-on-zero.ll @@ -211,6 +211,29 @@ else: ret i32 %l } +define i32 @sub10_else_drop_nuw(i32 %a) { +; CHECK-LABEL: @sub10_else_drop_nuw( +; CHECK-NEXT: entry: +; CHECK-NEXT: [[L:%.*]] = sub i32 [[A:%.*]], 10 +; CHECK-NEXT: [[TMP0:%.*]] = icmp eq i32 [[L]], 0 +; CHECK-NEXT: br i1 [[TMP0]], label [[THEN:%.*]], label [[ELSE:%.*]] +; CHECK: then: +; CHECK-NEXT: ret i32 0 +; CHECK: else: +; CHECK-NEXT: ret i32 [[L]] +; +entry: + %c = icmp eq i32 %a, 10 + br i1 %c, label %then, label %else + +then: + ret i32 0 + +else: + %l = sub nuw i32 %a, 10 + ret i32 %l +} + define i32 @subm10_then(i32 %a) { ; CHECK-LABEL: @subm10_then( ; CHECK-NEXT: entry: diff --git a/llvm/test/Transforms/CodeGenPrepare/RISCV/convert-to-eqz.ll b/llvm/test/Transforms/CodeGenPrepare/RISCV/convert-to-eqz.ll new file mode 100644 index 00000000000000..a6909d14913494 --- /dev/null +++ b/llvm/test/Transforms/CodeGenPrepare/RISCV/convert-to-eqz.ll @@ -0,0 +1,80 @@ +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4 +; RUN: opt -codegenprepare -S -mtriple=riscv64 < %s | FileCheck %s + +define i8 @hoist_add(i8 %x) { +; CHECK-LABEL: define i8 @hoist_add( +; CHECK-SAME: i8 [[X:%.*]]) { +; CHECK-NEXT: entry: +; CHECK-NEXT: [[INC:%.*]] = add i8 [[X]], 1 +; CHECK-NEXT: [[TMP0:%.*]] = icmp eq i8 [[INC]], 0 +; CHECK-NEXT: br i1 [[TMP0]], label [[EXIT:%.*]], label [[IF_THEN:%.*]] +; CHECK: if.then: +; CHECK-NEXT: br label [[EXIT]] +; CHECK: exit: +; CHECK-NEXT: [[RETVAL:%.*]] = phi i8 [ [[INC]], [[IF_THEN]] ], [ -1, [[ENTRY:%.*]] ] +; CHECK-NEXT: ret i8 [[RETVAL]] +; +entry: + %cmp = icmp eq i8 %x, -1 + br i1 %cmp, label %exit, label %if.then + +if.then: + %inc = add nuw nsw i8 %x, 1 + br label %exit + +exit: + %retval = phi i8 [ %inc, %if.then ], [ -1, %entry ] + ret i8 %retval +} + +define i8 @hoist_lshr(i8 %x) { +; CHECK-LABEL: define i8 @hoist_lshr( +; CHECK-SAME: i8 [[X:%.*]]) { +; CHECK-NEXT: entry: +; CHECK-NEXT: [[INC:%.*]] = lshr i8 [[X]], 3 +; CHECK-NEXT: [[TMP0:%.*]] = icmp eq i8 [[INC]], 0 +; CHECK-NEXT: br i1 [[TMP0]], label [[EXIT:%.*]], label [[IF_THEN:%.*]] +; CHECK: if.then: +; CHECK-NEXT: br label [[EXIT]] +; CHECK: exit: +; CHECK-NEXT: [[RETVAL:%.*]] = phi i8 [ [[INC]], [[IF_THEN]] ], [ -1, [[ENTRY:%.*]] ] +; CHECK-NEXT: ret i8 [[RETVAL]] +; +entry: + %cmp = icmp ult i8 %x, 8 + br i1 %cmp, label %exit, label %if.then + +if.then: + %inc = lshr exact i8 %x, 3 + br label %exit + +exit: + %retval = phi i8 [ %inc, %if.then ], [ -1, %entry ] + ret i8 %retval +} + +define i8 @nomove_add(i8 %x) { +; CHECK-LABEL: define i8 @nomove_add( +; CHECK-SAME: i8 [[X:%.*]]) { +; CHECK-NEXT: entry: +; CHECK-NEXT: [[INC:%.*]] = add i8 [[X]], 1 +; CHECK-NEXT: [[TMP0:%.*]] = icmp eq i8 [[INC]], 0 +; CHECK-NEXT: br i1 [[TMP0]], label [[EXIT:%.*]], label [[IF_THEN:%.*]] +; CHECK: if.then: +; CHECK-NEXT: br label [[EXIT]] +; CHECK: exit: +; CHECK-NEXT: [[RETVAL:%.*]] = phi i8 [ [[INC]], [[IF_THEN]] ], [ -1, [[ENTRY:%.*]] ] +; CHECK-NEXT: ret i8 [[RETVAL]] +; +entry: + %inc = add nuw nsw i8 %x, 1 + %cmp = icmp eq i8 %x, -1 + br i1 %cmp, label %exit, label %if.then + +if.then: + br label %exit + +exit: + %retval = phi i8 [ %inc, %if.then ], [ -1, %entry ] + ret i8 %retval +} ``````````
tstellar commented 2 weeks ago

Hi @dtcxzyw (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR.