[X86] Remove FP0-6 operands from call instructions in FPStackifier pass. Only count defs as returns.

[craig.topper]

Summary

All FP0-6 operands should be removed by the FP stackifier. By
removing these we fix the machine verifier error in PR39437.

I've also made it so that only defs are counted for STReturns
which removes what I think were extra stack cleanup instructions.

[craig.topper]

Remove bad assert. The assert was checking the calling convention of the function we're compiling, but we need the calling convention of the function that the call instruction references. But I don't think you can get that at this level.

[RKSimon]

LGTM

[craig.topper]

Committed as aa17d31edb00c66461093b5a7cd2f4a35dc143e9

llvm/lib/Target/X86/X86FloatingPoint.cpp

 }
 
 
 //===----------------------------------------------------------------------===//
 // Instruction transformation implementation
 //===----------------------------------------------------------------------===//
 
 void FPS::handleCall(MachineBasicBlock::iterator &I) {
+  MachineInstr &MI = *I;
   unsigned STReturns = 0;
   const MachineFunction* MF = I->getParent()->getParent();
 
-  for (const auto &MO : I->operands()) {
-    if (!MO.isReg())
+  for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
+    MachineOperand &Op = MI.getOperand(i);
+    if (!Op.isReg() || Op.getReg() < X86::FP0 || Op.getReg() > X86::FP6)
       continue;
 
-    unsigned R = MO.getReg() - X86::FP0;
+    assert(Op.isImplicit() && "Expected implicit def/use");
 
-    if (R < 8) {
-      if (MF->getFunction().getCallingConv() != CallingConv::X86_RegCall) {
-        assert(MO.isDef() && MO.isImplicit());
-      }
+    if (Op.isDef())
+      STReturns |= 1 << getFPReg(Op);
 
-      STReturns |= 1 << R;
-    }
+    // Remove the operand so that later passes don't see it.
+    MI.RemoveOperand(i);
+    --i;
+    --e;
   }
 
   unsigned N = countTrailingOnes(STReturns);
 
   // FP registers used for function return must be consecutive starting at
   // FP0
   assert(STReturns == 0 || (isMask_32(STReturns) && N <= 2));
 

llvm/test/CodeGen/X86/avx512-regcall-NoMask.ll

 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; FIXME: Fix machine verifier issues and remove -verify-machineinstrs=0. PR39437.
-; RUN: llc < %s -mtriple=i386-pc-win32       -mattr=+avx512f -mattr=+avx512vl -mattr=+avx512bw -mattr=+avx512dq -verify-machineinstrs=0  | FileCheck %s --check-prefix=X32
-; RUN: llc < %s -mtriple=x86_64-win32        -mattr=+avx512f -mattr=+avx512vl -mattr=+avx512bw -mattr=+avx512dq -verify-machineinstrs=0  | FileCheck %s --check-prefix=WIN64
-; RUN: llc < %s -mtriple=x86_64-linux-gnu    -mattr=+avx512f -mattr=+avx512vl -mattr=+avx512bw -mattr=+avx512dq -verify-machineinstrs=0  | FileCheck %s --check-prefix=LINUXOSX64
+; RUN: llc < %s -mtriple=i386-pc-win32       -mattr=+avx512f -mattr=+avx512vl -mattr=+avx512bw -mattr=+avx512dq -verify-machineinstrs  | FileCheck %s --check-prefix=X32
+; RUN: llc < %s -mtriple=x86_64-win32        -mattr=+avx512f -mattr=+avx512vl -mattr=+avx512bw -mattr=+avx512dq -verify-machineinstrs  | FileCheck %s --check-prefix=WIN64
+; RUN: llc < %s -mtriple=x86_64-linux-gnu    -mattr=+avx512f -mattr=+avx512vl -mattr=+avx512bw -mattr=+avx512dq -verify-machineinstrs  | FileCheck %s --check-prefix=LINUXOSX64
 
 ; Test regcall when receiving/returning i1
 define x86_regcallcc i1 @test_argReti1(i1 %a)  {
 ; X32-LABEL: test_argReti1:
 ; X32:       # %bb.0:
 ; X32-NEXT:    incb %al
 ; X32-NEXT:    # kill: def $al killed $al killed $eax
 ; X32-NEXT:    retl

 
 define x86_regcallcc double @test_CallargParamf80(x86_fp80 %a)  {
 ; X32-LABEL: test_CallargParamf80:
 ; X32:       # %bb.0:
 ; X32-NEXT:    pushl %esp
 ; X32-NEXT:    fadd %st, %st(0)
 ; X32-NEXT:    calll _test_argParamf80
 ; X32-NEXT:    vaddsd %xmm0, %xmm0, %xmm0
-; X32-NEXT:    fstp %st(0)
 ; X32-NEXT:    popl %esp
 ; X32-NEXT:    retl
 ;
 ; WIN64-LABEL: test_CallargParamf80:
 ; WIN64:       # %bb.0:
 ; WIN64-NEXT:    pushq %rsp
 ; WIN64-NEXT:    .seh_pushreg %rsp
 ; WIN64-NEXT:    .seh_endprologue
 ; WIN64-NEXT:    fadd %st, %st(0)
 ; WIN64-NEXT:    callq test_argParamf80
 ; WIN64-NEXT:    vaddsd %xmm0, %xmm0, %xmm0
-; WIN64-NEXT:    fstp %st(0)
 ; WIN64-NEXT:    popq %rsp
 ; WIN64-NEXT:    retq
 ; WIN64-NEXT:    .seh_handlerdata
 ; WIN64-NEXT:    .text
 ; WIN64-NEXT:    .seh_endproc
 ;
 ; LINUXOSX64-LABEL: test_CallargParamf80:
 ; LINUXOSX64:       # %bb.0:
 ; LINUXOSX64-NEXT:    pushq %rsp
 ; LINUXOSX64-NEXT:    .cfi_def_cfa_offset 16
 ; LINUXOSX64-NEXT:    .cfi_offset %rsp, -16
 ; LINUXOSX64-NEXT:    fadd %st, %st(0)
 ; LINUXOSX64-NEXT:    callq test_argParamf80
 ; LINUXOSX64-NEXT:    vaddsd %xmm0, %xmm0, %xmm0
-; LINUXOSX64-NEXT:    fstp %st(0)
 ; LINUXOSX64-NEXT:    popq %rsp
 ; LINUXOSX64-NEXT:    .cfi_def_cfa_offset 8
 ; LINUXOSX64-NEXT:    retq
   %b = fadd x86_fp80 %a, %a
   %c = call x86_regcallcc double @test_argParamf80(x86_fp80 %b)
   %d = fadd double %c, %c
   ret double %d
 }