[llvm] 09b1cfc - [InstCombine] Add additional test case for (add (zext (add nuw X, C2), C1). NFC

[Craig Topper via llvm-commits]

Author: Craig Topper
Date: 2024-07-12T07:33:39-07:00
New Revision: 09b1cfceb62332ebf8e5d319ee048492a709995d

URL: https://github.com/llvm/llvm-project/commit/09b1cfceb62332ebf8e5d319ee048492a709995d
DIFF: https://github.com/llvm/llvm-project/commit/09b1cfceb62332ebf8e5d319ee048492a709995d.diff

LOG: [InstCombine] Add additional test case for (add (zext (add nuw X, C2), C1). NFC

Add test where the zext has an additional use, but the entire
expression can be replaced with (zext X). Folding even though there
is an additional use would not increase the number of instructions.

Added: 
    

Modified: 
    llvm/test/Transforms/InstCombine/add.ll

Removed: 
    


################################################################################
diff  --git a/llvm/test/Transforms/InstCombine/add.ll b/llvm/test/Transforms/InstCombine/add.ll
index 8b3ecaf25cd9d..2f914a2e58867 100644
--- a/llvm/test/Transforms/InstCombine/add.ll
+++ b/llvm/test/Transforms/InstCombine/add.ll
@@ -951,6 +951,21 @@ define i64 @test41(i32 %a) {
   ret i64 %sub
 }
 
+define i64 @test41_multiuse_constants_cancel(i32 %a) {
+; CHECK-LABEL: @test41_multiuse_constants_cancel(
+; CHECK-NEXT:    [[ADD:%.*]] = add nuw i32 [[A:%.*]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i32 [[ADD]] to i64
+; CHECK-NEXT:    [[REASS_ADD:%.*]] = shl nuw nsw i64 [[ZEXT]], 1
+; CHECK-NEXT:    [[EXTRAUSE:%.*]] = add nsw i64 [[REASS_ADD]], -1
+; CHECK-NEXT:    ret i64 [[EXTRAUSE]]
+;
+  %add = add nuw i32 %a, 1
+  %zext = zext i32 %add to i64
+  %sub = add i64 %zext, -1
+  %extrause = add i64 %zext, %sub
+  ret i64 %extrause
+}
+
 ; (add (zext (add nuw X, C2)), C) --> (zext (add nuw X, C2 + C))
 
 define <2 x i64> @test41vec(<2 x i32> %a) {