[llvm] [X86] Set default rounding mode round to nearest for llvm.set.rounding (PR #160823)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-x86

Author: None (JaydeepChauhan14)

<details>
<summary>Changes</summary>

- Fix https://github.com/llvm/llvm-project/pull/156591#issuecomment-3335218842
- As per https://cdrdv2.intel.com/v1/dl/getContent/671200 default rounding mode is **round to nearest**. 

---
Full diff: https://github.com/llvm/llvm-project/pull/160823.diff


2 Files Affected:

- (modified) llvm/lib/Target/X86/GISel/X86LegalizerInfo.cpp (+1) 
- (modified) llvm/lib/Target/X86/X86ISelLowering.cpp (+1-1) 


``````````diff
diff --git a/llvm/lib/Target/X86/GISel/X86LegalizerInfo.cpp b/llvm/lib/Target/X86/GISel/X86LegalizerInfo.cpp
index ee9760f881ae9..143c4c43e611a 100644
--- a/llvm/lib/Target/X86/GISel/X86LegalizerInfo.cpp
+++ b/llvm/lib/Target/X86/GISel/X86LegalizerInfo.cpp
@@ -905,6 +905,7 @@ bool X86LegalizerInfo::legalizeSETROUNDING(MachineInstr &MI,
     int FieldVal = X86::getRoundingModeX86(RM);
 
     if (FieldVal == X86::rmInvalid) {
+      FieldVal = X86::rmToNearest;
       LLVMContext &C = MF.getFunction().getContext();
       C.diagnose(DiagnosticInfoUnsupported(
           MF.getFunction(), "rounding mode is not supported by X86 hardware",
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 80fbcaa562032..57cf66e5275e3 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -28714,11 +28714,11 @@ SDValue X86TargetLowering::LowerSET_ROUNDING(SDValue Op,
     int FieldVal = X86::getRoundingModeX86(RM);
 
     if (FieldVal == X86::rmInvalid) {
+      FieldVal = X86::rmToNearest;
       LLVMContext &C = MF.getFunction().getContext();
       C.diagnose(DiagnosticInfoUnsupported(
           MF.getFunction(), "rounding mode is not supported by X86 hardware",
           DiagnosticLocation(DL.getDebugLoc()), DS_Error));
-      return {};
     }
     RMBits = DAG.getConstant(FieldVal, DL, MVT::i16);
   } else {

``````````

</details>


https://github.com/llvm/llvm-project/pull/160823