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

[Phoebe Wang 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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phoebewang wrote:

But I'd argue that strictfp has two independent controls: "rounding mode" and "exceptions". It's a reasonable usage to only care about "rounding mode" and ignore "exceptions". For this case, scheduling non-RC-def inline asm among other FP instructions is permitted.

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