[InstSimplify] Avoid use of ConstantExpr::getICmp. NFC

[topperc]

As I understand ICmp ConstantExpr are planned to be removed.

[llvmbot]

@llvm/pr-subscribers-llvm-analysis

Changes

As I understand ICmp ConstantExpr are planned to be removed.

---

Full diff: https://github.com/llvm/llvm-project/pull/67873.diff

1 Files Affected:

• (modified) llvm/lib/Analysis/InstructionSimplify.cpp (+4-4)

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 40a8f6a155b23d2..5bdff48f79b4657 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -3916,12 +3916,12 @@ static Value *simplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
           // is non-negative then LHS <s RHS.
           case ICmpInst::ICMP_SGT:
           case ICmpInst::ICMP_SGE:
-            return ConstantExpr::getICmp(ICmpInst::ICMP_SLT, C,
-                                         Constant::getNullValue(C->getType()));
+            return ConstantFoldCompareInstruction(
+                ICmpInst::ICMP_SLT, C, Constant::getNullValue(C->getType()));
           case ICmpInst::ICMP_SLT:
           case ICmpInst::ICMP_SLE:
-            return ConstantExpr::getICmp(ICmpInst::ICMP_SGE, C,
-                                         Constant::getNullValue(C->getType()));
+            return ConstantFoldCompareInstruction(
+                ICmpInst::ICMP_SGE, C, Constant::getNullValue(C->getType()));
           }
         }
       }

[nikic]

Use ConstantFoldCompareInstOperands instead, which is DataLayout-aware.

[topperc]

Does that matter here? C came from m_ImmConstant and we're comparing it to null.

[nikic]

It makes no functional difference here, but you should never use the functions declared in llvm/IR/ConstantFold.h, only those in llvm/Analysis/ConstantFolding.h, which is the public API. We should maybe move the former into the detail namespace to make this clearer.

[nikic]

Or possibly we can move the ConstantFolder implementation out-of-line (if it causes no compile-time impact), because that's the only reason ConstantFold.h is a public header at all.