[llvm] [X86] LowerAsmOperandForConstraint - ensure we treat L constraint immediates as signed constants (PR #171098)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-x86

Author: Simon Pilgrim (RKSimon)

<details>
<summary>Changes</summary>

getTargetConstant no longer tolerates sign-extended values that can't be represented by the appropriate APInt bitwidth, which now defaults to unsigned behaviour.

Fixes #<!-- -->166058

---
Full diff: https://github.com/llvm/llvm-project/pull/171098.diff


2 Files Affected:

- (modified) llvm/lib/Target/X86/X86ISelLowering.cpp (+2-2) 
- (added) llvm/test/CodeGen/X86/pr166058.ll (+15) 


``````````diff
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index d0ae75b2e6785..8f22f8c3618a6 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -61928,8 +61928,8 @@ void X86TargetLowering::LowerAsmOperandForConstraint(SDValue Op,
     if (auto *C = dyn_cast<ConstantSDNode>(Op)) {
       if (C->getZExtValue() == 0xff || C->getZExtValue() == 0xffff ||
           (Subtarget.is64Bit() && C->getZExtValue() == 0xffffffff)) {
-        Result = DAG.getTargetConstant(C->getSExtValue(), SDLoc(Op),
-                                       Op.getValueType());
+        Result = DAG.getSignedTargetConstant(C->getSExtValue(), SDLoc(Op),
+                                             Op.getValueType());
         break;
       }
     }
diff --git a/llvm/test/CodeGen/X86/pr166058.ll b/llvm/test/CodeGen/X86/pr166058.ll
new file mode 100644
index 0000000000000..2e0bb6036820f
--- /dev/null
+++ b/llvm/test/CodeGen/X86/pr166058.ll
@@ -0,0 +1,15 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
+; RUN: llc -mtriple=x86_64-- | FileCheck %s
+
+ at out = global i32 0, align 4
+define void @bar() {
+; CHECK-LABEL: bar:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    movq out at GOTPCREL(%rip), %rax
+; CHECK-NEXT:    #APP
+; CHECK-NEXT:    addq $-1, (%rax)
+; CHECK-NEXT:    #NO_APP
+; CHECK-NEXT:    retq
+  call void asm "addq $1,$0", "=*m,L,~{dirflag},~{fpsr},~{flags}"(ptr elementtype(i32) @out, i32 -1)
+  ret void
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/171098