[llvm] [X86][ConstraintFP] Model rounding control registers for inline asm (PR #92846)

[Matt Arsenault via llvm-commits]

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@@ -669,8 +669,14 @@ const MCPhysReg *X86TargetLowering::getScratchRegisters(CallingConv::ID) const {
   return ScratchRegs;
 }
 
-ArrayRef<MCPhysReg> X86TargetLowering::getRoundingControlRegisters() const {
+ArrayRef<MCPhysReg>
+X86TargetLowering::getRoundingControlRegisters(const char *AsmStr) const {
   static const MCPhysReg RCRegs[] = {X86::FPCW, X86::MXCSR};
+  if (AsmStr) {
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arsenm wrote:

I think any attempt at parsing the content of the string is a bad path to go down. Why is this worthwhile over what was here before, and just unconditionally add it? 

https://github.com/llvm/llvm-project/pull/92846