[llvm] [CVP] Infer nneg on zext when forming from non-negative sext. (PR #70715)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Craig Topper (topperc)

<details>
<summary>Changes</summary>

Builds on #<!-- -->67982 which recently introduced the nneg flag on a zext instruction.

---
Full diff: https://github.com/llvm/llvm-project/pull/70715.diff


4 Files Affected:

- (modified) llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp (+1) 
- (modified) llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll (+1-1) 
- (modified) llvm/test/Transforms/CorrelatedValuePropagation/sext.ll (+2-2) 
- (modified) llvm/test/Transforms/PhaseOrdering/AArch64/loopflatten.ll (+2-2) 


``````````diff
diff --git a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
index 9043c434313fedc..99b4628cc68dd00 100644
--- a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -1017,6 +1017,7 @@ static bool processSExt(SExtInst *SDI, LazyValueInfo *LVI) {
   auto *ZExt = CastInst::CreateZExtOrBitCast(Base, SDI->getType(), "", SDI);
   ZExt->takeName(SDI);
   ZExt->setDebugLoc(SDI->getDebugLoc());
+  ZExt->setNonNeg();
   SDI->replaceAllUsesWith(ZExt);
   SDI->eraseFromParent();
 
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll b/llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll
index 8e5ec878bb894fa..7ec1028d65e0e9f 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll
@@ -519,7 +519,7 @@ define i16 @ashr_convert(i16 noundef %x, i16 %y) {
 
 define i32 @sext_convert(i16 noundef %x) {
 ; CHECK-LABEL: @sext_convert(
-; CHECK-NEXT:    [[EXT:%.*]] = zext i16 [[X:%.*]] to i32
+; CHECK-NEXT:    [[EXT:%.*]] = zext nneg i16 [[X:%.*]] to i32
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp sge i16 [[X]], 0
 ; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[CMP]], i32 [[EXT]], i32 24
 ; CHECK-NEXT:    ret i32 [[SEL]]
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/sext.ll b/llvm/test/Transforms/CorrelatedValuePropagation/sext.ll
index 62e0bc036e769cb..0db520bfc68a228 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/sext.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/sext.ll
@@ -18,7 +18,7 @@ define void @test1(i32 %n) {
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[A]], -1
 ; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
 ; CHECK:       for.body:
-; CHECK-NEXT:    [[EXT_WIDE1:%.*]] = zext i32 [[A]] to i64
+; CHECK-NEXT:    [[EXT_WIDE1:%.*]] = zext nneg i32 [[A]] to i64
 ; CHECK-NEXT:    call void @use64(i64 [[EXT_WIDE1]])
 ; CHECK-NEXT:    [[EXT]] = trunc i64 [[EXT_WIDE1]] to i32
 ; CHECK-NEXT:    br label [[FOR_COND]]
@@ -85,7 +85,7 @@ define void @test3(i32 %n) {
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[N:%.*]], -1
 ; CHECK-NEXT:    br i1 [[CMP]], label [[BB:%.*]], label [[EXIT:%.*]]
 ; CHECK:       bb:
-; CHECK-NEXT:    [[EXT_WIDE1:%.*]] = zext i32 [[N]] to i64
+; CHECK-NEXT:    [[EXT_WIDE1:%.*]] = zext nneg i32 [[N]] to i64
 ; CHECK-NEXT:    call void @use64(i64 [[EXT_WIDE1]])
 ; CHECK-NEXT:    [[EXT:%.*]] = trunc i64 [[EXT_WIDE1]] to i32
 ; CHECK-NEXT:    br label [[EXIT]]
diff --git a/llvm/test/Transforms/PhaseOrdering/AArch64/loopflatten.ll b/llvm/test/Transforms/PhaseOrdering/AArch64/loopflatten.ll
index 2150026ab5e0dfb..77f53ad56e1cc46 100644
--- a/llvm/test/Transforms/PhaseOrdering/AArch64/loopflatten.ll
+++ b/llvm/test/Transforms/PhaseOrdering/AArch64/loopflatten.ll
@@ -12,8 +12,8 @@ define dso_local void @_Z3fooPiii(ptr %A, i32 %N, i32 %M) #0 {
 ; CHECK-NEXT:    [[OR_COND:%.*]] = select i1 [[CMP3]], i1 [[CMP21]], i1 false
 ; CHECK-NEXT:    br i1 [[OR_COND]], label [[FOR_COND1_PREHEADER_LR_PH_SPLIT_US:%.*]], label [[FOR_COND_CLEANUP:%.*]]
 ; CHECK:       for.cond1.preheader.lr.ph.split.us:
-; CHECK-NEXT:    [[TMP0:%.*]] = zext i32 [[M]] to i64
-; CHECK-NEXT:    [[TMP1:%.*]] = zext i32 [[N]] to i64
+; CHECK-NEXT:    [[TMP0:%.*]] = zext nneg i32 [[M]] to i64
+; CHECK-NEXT:    [[TMP1:%.*]] = zext nneg i32 [[N]] to i64
 ; CHECK-NEXT:    [[FLATTEN_TRIPCOUNT:%.*]] = mul nuw nsw i64 [[TMP0]], [[TMP1]]
 ; CHECK-NEXT:    br label [[FOR_COND1_PREHEADER_US:%.*]]
 ; CHECK:       for.cond1.preheader.us:

``````````

</details>


https://github.com/llvm/llvm-project/pull/70715