[llvm] [X86] Fix 32-bit immediate assertion and convert into backend error (PR #123872)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-x86

Author: Wesley Wiser (wesleywiser)

<details>
<summary>Changes</summary>

The assertion previously did not work correctly because the operand was being truncated to an `int` prior to comparison.

Change the assertion into a a reported error as suggested in https://github.com/llvm/llvm-project/pull/101840#issuecomment-2304992425 by @<!-- -->arsenm

---
Full diff: https://github.com/llvm/llvm-project/pull/123872.diff


1 Files Affected:

- (modified) llvm/lib/Target/X86/X86RegisterInfo.cpp (+4-5) 


``````````diff
diff --git a/llvm/lib/Target/X86/X86RegisterInfo.cpp b/llvm/lib/Target/X86/X86RegisterInfo.cpp
index 4faf8bca4f9e02..8a35de5ca98f11 100644
--- a/llvm/lib/Target/X86/X86RegisterInfo.cpp
+++ b/llvm/lib/Target/X86/X86RegisterInfo.cpp
@@ -965,11 +965,10 @@ X86RegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
   }
 
   if (MI.getOperand(FIOperandNum+3).isImm()) {
-    // Offset is a 32-bit integer.
-    int Imm = (int)(MI.getOperand(FIOperandNum + 3).getImm());
-    int Offset = FIOffset + Imm;
-    assert((!Is64Bit || isInt<32>((long long)FIOffset + Imm)) &&
-           "Requesting 64-bit offset in 32-bit immediate!");
+    int64_t Imm = MI.getOperand(FIOperandNum + 3).getImm();
+    int Offset = FIOffset + (int)Imm;
+    if (!Is64Bit && !isInt<32>((int64_t)FIOffset + Imm))
+      MI.emitGenericError(("Requesting 64-bit offset in 32-bit immediate: " + MF.getName()).str());
     if (Offset != 0 || !tryOptimizeLEAtoMOV(II))
       MI.getOperand(FIOperandNum + 3).ChangeToImmediate(Offset);
   } else {

``````````

</details>


https://github.com/llvm/llvm-project/pull/123872