[InstCombine] Fix missing argument typo in InstCombinerImpl::foldICmpShlConstant

[dtcxzyw]

Closes #94897.

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: Yingwei Zheng (dtcxzyw)

Changes

Closes #94897.

---

Full diff: https://github.com/llvm/llvm-project/pull/94899.diff

2 Files Affected:

• (modified) llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp (+4-3)
• (modified) llvm/test/Transforms/InstCombine/icmp.ll (+10)

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 89193f8ff94b6..9965825e582be 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -2441,9 +2441,10 @@ Instruction *InstCombinerImpl::foldICmpShlConstant(ICmpInst &Cmp,
       Type *TruncTy = ShType->getWithNewBitWidth(TypeBits - Amt);
       Constant *NewC =
           ConstantInt::get(TruncTy, RHSC.ashr(*ShiftAmt).trunc(TypeBits - Amt));
-      return new ICmpInst(
-          CmpPred, Builder.CreateTrunc(X, TruncTy, "", Shl->hasNoSignedWrap()),
-          NewC);
+      return new ICmpInst(CmpPred,
+                          Builder.CreateTrunc(X, TruncTy, "", /*IsNUW=*/false,
+                                              Shl->hasNoSignedWrap()),
+                          NewC);
     }
   }
 
diff --git a/llvm/test/Transforms/InstCombine/icmp.ll b/llvm/test/Transforms/InstCombine/icmp.ll
index 4dbe2fc88ff71..723dbbc7101dc 100644
--- a/llvm/test/Transforms/InstCombine/icmp.ll
+++ b/llvm/test/Transforms/InstCombine/icmp.ll
@@ -5295,3 +5295,13 @@ define i1 @test_icmp_shl_sgt(i64 %x) {
   %cmp = icmp sgt i64 %shl, 8589934591
   ret i1 %cmp
 }
+
+define i1 @pr94897(i32 range(i32 -2147483648, 0) %x) {
+; CHECK-LABEL: @pr94897(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ugt i32 [[X:%.*]], -3
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %shl = shl nsw i32 %x, 24
+  %cmp = icmp ugt i32 %shl, -50331648
+  ret i1 %cmp
+}

[nikic]

I didn't even notice that #92773 also made changes to flag preservation -- it seems like that part of the PR was untested? At least I don't see any trunc nuw/nsw in the tests. Can you please add coverage?

[dtcxzyw]

I didn't even notice that #92773 also made changes to flag preservation -- it seems like that part of the PR was untested? At least I don't see any trunc nuw/nsw in the tests. Can you please add coverage?

Done.

[goldsteinn]

LGTM

[nikic]

LGTM