[llvm] 02455be - [InstCombine] remove unnecessary use check on X >>exact == 0 fold

[Sanjay Patel via llvm-commits]

Author: Sanjay Patel
Date: 2022-01-14T12:52:16-05:00
New Revision: 02455bea6b9d4bbbb58e9c30f3615cbe472a9477

URL: https://github.com/llvm/llvm-project/commit/02455bea6b9d4bbbb58e9c30f3615cbe472a9477
DIFF: https://github.com/llvm/llvm-project/commit/02455bea6b9d4bbbb58e9c30f3615cbe472a9477.diff

LOG: [InstCombine] remove unnecessary use check on X >>exact == 0 fold

The transform replaces one icmp with another, so we should
not care if the shift has another use.

Added: 
    

Modified: 
    llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
    llvm/test/Transforms/InstCombine/icmp-shr.ll

Removed: 
    


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diff  --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index c14e28dc4032b..079afa992aa51 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -2213,7 +2213,7 @@ Instruction *InstCombinerImpl::foldICmpShrConstant(ICmpInst &Cmp,
   // icmp eq/ne (shr X, Y), 0 --> icmp eq/ne X, 0
   Value *X = Shr->getOperand(0);
   CmpInst::Predicate Pred = Cmp.getPredicate();
-  if (Cmp.isEquality() && Shr->isExact() && Shr->hasOneUse() && C.isZero())
+  if (Cmp.isEquality() && Shr->isExact() && C.isZero())
     return new ICmpInst(Pred, X, Cmp.getOperand(1));
 
   const APInt *ShiftVal;

diff  --git a/llvm/test/Transforms/InstCombine/icmp-shr.ll b/llvm/test/Transforms/InstCombine/icmp-shr.ll
index 10b7362c9fc2d..45f8eb02b57c9 100644
--- a/llvm/test/Transforms/InstCombine/icmp-shr.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-shr.ll
@@ -508,7 +508,7 @@ define i1 @ashr_exact_ne_0_uses(i32 %X, i32 %Y) {
 ; CHECK-LABEL: @ashr_exact_ne_0_uses(
 ; CHECK-NEXT:    [[A:%.*]] = ashr exact i32 [[X:%.*]], [[Y:%.*]]
 ; CHECK-NEXT:    call void @foo(i32 [[A]])
-; CHECK-NEXT:    [[B:%.*]] = icmp ne i32 [[A]], 0
+; CHECK-NEXT:    [[B:%.*]] = icmp ne i32 [[X]], 0
 ; CHECK-NEXT:    ret i1 [[B]]
 ;
   %A = ashr exact i32 %X, %Y
@@ -541,7 +541,7 @@ define i1 @lshr_exact_eq_0_uses(i32 %X, i32 %Y) {
 ; CHECK-LABEL: @lshr_exact_eq_0_uses(
 ; CHECK-NEXT:    [[A:%.*]] = lshr exact i32 [[X:%.*]], [[Y:%.*]]
 ; CHECK-NEXT:    call void @foo(i32 [[A]])
-; CHECK-NEXT:    [[B:%.*]] = icmp eq i32 [[A]], 0
+; CHECK-NEXT:    [[B:%.*]] = icmp eq i32 [[X]], 0
 ; CHECK-NEXT:    ret i1 [[B]]
 ;
   %A = lshr exact i32 %X, %Y