Model inline asm constraint which ties an input to an output register as machine operand TIED_TO constraint. This eliminated the need to pre-allocate registers for these. This also allows register allocator can eliminate the unneeded copies.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@67512 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86FloatingPoint.cpp b/lib/Target/X86/X86FloatingPoint.cpp
index e0dbf99..8862428 100644
--- a/lib/Target/X86/X86FloatingPoint.cpp
+++ b/lib/Target/X86/X86FloatingPoint.cpp
@@ -1017,9 +1017,37 @@
case X86::MOV_Fp8032:
case X86::MOV_Fp8064:
case X86::MOV_Fp8080: {
- unsigned SrcReg = getFPReg(MI->getOperand(1));
- unsigned DestReg = getFPReg(MI->getOperand(0));
+ const MachineOperand &MO1 = MI->getOperand(1);
+ unsigned SrcReg = getFPReg(MO1);
+ const MachineOperand &MO0 = MI->getOperand(0);
+ // These can be created due to inline asm. Two address pass can introduce
+ // copies from RFP registers to virtual registers.
+ if (MO0.getReg() == X86::ST0 && SrcReg == 0) {
+ assert(MO1.isKill());
+ // Treat %ST0<def> = MOV_Fp8080 %FP0<kill>
+ // like FpSET_ST0_80 %FP0<kill>, %ST0<imp-def>
+ assert((StackTop == 1 || StackTop == 2)
+ && "Stack should have one or two element on it to return!");
+ --StackTop; // "Forget" we have something on the top of stack!
+ break;
+ } else if (MO0.getReg() == X86::ST1 && SrcReg == 1) {
+ assert(MO1.isKill());
+ // Treat %ST1<def> = MOV_Fp8080 %FP1<kill>
+ // like FpSET_ST1_80 %FP0<kill>, %ST1<imp-def>
+ // StackTop can be 1 if a FpSET_ST0_* was before this. Exchange them.
+ if (StackTop == 1) {
+ BuildMI(*MBB, I, dl, TII->get(X86::XCH_F)).addReg(X86::ST1);
+ NumFXCH++;
+ StackTop = 0;
+ break;
+ }
+ assert(StackTop == 2 && "Stack should have two element on it to return!");
+ --StackTop; // "Forget" we have something on the top of stack!
+ break;
+ }
+
+ unsigned DestReg = getFPReg(MO0);
if (MI->killsRegister(X86::FP0+SrcReg)) {
// If the input operand is killed, we can just change the owner of the
// incoming stack slot into the result.