[InstCombine] Regard zext nneg as sext when folding add(zext neg(add))

[ZelinMa557]

fixes #88348
proof:
https://alive2.llvm.org/ce/z/fJnM7t
test will be added later

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@llvm/pr-subscribers-llvm-transforms

Author: None (ZelinMa557)

Changes

fix the issue #88348

---

Full diff: https://github.com/llvm/llvm-project/pull/88887.diff

1 Files Affected:

• (modified) llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp (+3-3)

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
index 07c50d866544b3..e659b5de395b35 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -828,9 +828,10 @@ static Instruction *foldNoWrapAdd(BinaryOperator &Add,
 
   // More general combining of constants in the wide type.
   // (sext (X +nsw NarrowC)) + C --> (sext X) + (sext(NarrowC) + C)
+  // or (zext nneg (X +nsw NarrowC)) + C --> (sext X) + (sext(NarrowC) + C)
   Constant *NarrowC;
-  if (match(Op0,
-            m_OneUse(m_SExt(m_NSWAddLike(m_Value(X), m_Constant(NarrowC)))))) {
+  if (match(Op0, m_OneUse(m_SExtLike(
+                     m_NSWAddLike(m_Value(X), m_Constant(NarrowC)))))) {
     Value *WideC = Builder.CreateSExt(NarrowC, Ty);
     Value *NewC = Builder.CreateAdd(WideC, Op1C);
     Value *WideX = Builder.CreateSExt(X, Ty);
@@ -844,7 +845,6 @@ static Instruction *foldNoWrapAdd(BinaryOperator &Add,
     Value *WideX = Builder.CreateZExt(X, Ty);
     return BinaryOperator::CreateAdd(WideX, NewC);
   }
-
   return nullptr;
 }
 

[XChy]

This patch lacks alive2 proof, tests, and so on.
Please read about https://llvm.org/docs/InstCombineContributorGuide.html

[ZelinMa557]

Thanks, i will take a look! @XChy

[ZelinMa557]

Hi, I have added the test and proof according to https://llvm.org/docs/InstCombineContributorGuide.html, can you take a look when it is convenient for you? @XChy @nikic @dtcxzyw

[dtcxzyw]

LGTM.

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