[llvm] [C API] Add getter/setter for samesign flag on icmp (PR #145247)

[Benji Smith via llvm-commits]

https://github.com/Benjins created https://github.com/llvm/llvm-project/pull/145247

This was added to the C++ API in https://github.com/llvm/llvm-project/pull/111419 so this change adds accessors in the C API, along with a couple tests.

>From f852fe72bdb6e61d5b4cc69bfce3ff34cc0a5ce3 Mon Sep 17 00:00:00 2001
From: Benji Smith <benjsith at gmail.com>
Date: Sun, 22 Jun 2025 15:53:39 -0400
Subject: [PATCH] [C API] Add getter/setter for samesign flag on icmp

This was added to the C++ API in https://github.com/llvm/llvm-project/pull/111419
so this change adds accessors in the C API, along with a couple tests.
---
 llvm/docs/ReleaseNotes.md         |  3 +++
 llvm/include/llvm-c/Core.h        | 18 ++++++++++++++++++
 llvm/lib/IR/Core.cpp              |  8 ++++++++
 llvm/test/Bindings/llvm-c/echo.ll |  8 ++++++++
 llvm/tools/llvm-c-test/echo.cpp   |  2 ++
 5 files changed, 39 insertions(+)

diff --git a/llvm/docs/ReleaseNotes.md b/llvm/docs/ReleaseNotes.md
index 0395f43c61953..95bcc1a1f3f55 100644
--- a/llvm/docs/ReleaseNotes.md
+++ b/llvm/docs/ReleaseNotes.md
@@ -251,6 +251,9 @@ Changes to the C API
 * Added ``LLVMDIBuilderCreateEnumeratorOfArbitraryPrecision`` for creating
   debugging metadata of enumerators larger than 64 bits.
 
+* Added ``LLVMGetICmpSameSign`` and ``LLVMSetICmpSameSign`` for the `samesign`
+  flag on `icmp` instructions.
+
 Changes to the CodeGen infrastructure
 -------------------------------------
 
diff --git a/llvm/include/llvm-c/Core.h b/llvm/include/llvm-c/Core.h
index 6857944e6875f..3f30ed92997b4 100644
--- a/llvm/include/llvm-c/Core.h
+++ b/llvm/include/llvm-c/Core.h
@@ -3675,6 +3675,24 @@ LLVMOpcode LLVMGetInstructionOpcode(LLVMValueRef Inst);
  */
 LLVMIntPredicate LLVMGetICmpPredicate(LLVMValueRef Inst);
 
+/**
+ * Get whether or not an icmp instruction has the samesign flag.
+ *
+ * This is only valid for instructions that correspond to llvm::ICmpInst.
+ *
+ * @see llvm::ICmpInst::hasSameSign()
+ */
+LLVMBool LLVMGetICmpSameSign(LLVMValueRef Inst);
+
+/**
+ * Set the samesign flag on an icmp instruction.
+ *
+ * This is only valid for instructions that correspond to llvm::ICmpInst.
+ *
+ * @see llvm::ICmpInst::setSameSign()
+ */
+void LLVMSetICmpSameSign(LLVMValueRef Inst, LLVMBool SameSign);
+
 /**
  * Obtain the float predicate of an instruction.
  *
diff --git a/llvm/lib/IR/Core.cpp b/llvm/lib/IR/Core.cpp
index 9810f04cc503c..f7ef4aa473ef5 100644
--- a/llvm/lib/IR/Core.cpp
+++ b/llvm/lib/IR/Core.cpp
@@ -2951,6 +2951,14 @@ LLVMIntPredicate LLVMGetICmpPredicate(LLVMValueRef Inst) {
   return (LLVMIntPredicate)0;
 }
 
+LLVMBool LLVMGetICmpSameSign(LLVMValueRef Inst) {
+  return unwrap<ICmpInst>(Inst)->hasSameSign();
+}
+
+void LLVMSetICmpSameSign(LLVMValueRef Inst, LLVMBool SameSign) {
+  unwrap<ICmpInst>(Inst)->setSameSign(SameSign);
+}
+
 LLVMRealPredicate LLVMGetFCmpPredicate(LLVMValueRef Inst) {
   if (FCmpInst *I = dyn_cast<FCmpInst>(unwrap(Inst)))
     return (LLVMRealPredicate)I->getPredicate();
diff --git a/llvm/test/Bindings/llvm-c/echo.ll b/llvm/test/Bindings/llvm-c/echo.ll
index 0a688afab6125..ab1771d1f879f 100644
--- a/llvm/test/Bindings/llvm-c/echo.ll
+++ b/llvm/test/Bindings/llvm-c/echo.ll
@@ -417,6 +417,14 @@ define ptr @test_gep_no_wrap_flags(ptr %0) {
   ret ptr %gep.nusw
 }
 
+define void @test_icmp_same_sign(i32 %a, i32 %b) {
+  %icmp.1 = icmp eq i32 %a, %b
+  %icmp.2 = icmp slt i32 %a, %b
+  %icmp.3 = icmp samesign eq i32 %a, %b
+  %icmp.4 = icmp samesign slt i32 %a, %b
+  ret void
+}
+
 !llvm.dbg.cu = !{!0, !2}
 !llvm.module.flags = !{!3}
 
diff --git a/llvm/tools/llvm-c-test/echo.cpp b/llvm/tools/llvm-c-test/echo.cpp
index 3ec40fdba0bad..026d815b43da7 100644
--- a/llvm/tools/llvm-c-test/echo.cpp
+++ b/llvm/tools/llvm-c-test/echo.cpp
@@ -823,9 +823,11 @@ struct FunCloner {
       }
       case LLVMICmp: {
         LLVMIntPredicate Pred = LLVMGetICmpPredicate(Src);
+        LLVMBool IsSameSign = LLVMGetICmpSameSign(Src);
         LLVMValueRef LHS = CloneValue(LLVMGetOperand(Src, 0));
         LLVMValueRef RHS = CloneValue(LLVMGetOperand(Src, 1));
         Dst = LLVMBuildICmp(Builder, Pred, LHS, RHS, Name);
+        LLVMSetICmpSameSign(Dst, IsSameSign);
         break;
       }
       case LLVMPHI: {