[PATCH] D72064: [X86] Remove FP0-6 operands from call instructions in FPStackifier pass. Only count defs as returns.

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: spatel, RKSimon.
Herald added a subscriber: hiraditya.
Herald added a project: LLVM.

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.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D72064

Files:
  llvm/lib/Target/X86/X86FloatingPoint.cpp
  llvm/test/CodeGen/X86/avx512-regcall-NoMask.ll


Index: llvm/test/CodeGen/X86/avx512-regcall-NoMask.ll
===================================================================
--- llvm/test/CodeGen/X86/avx512-regcall-NoMask.ll
+++ llvm/test/CodeGen/X86/avx512-regcall-NoMask.ll
@@ -1,8 +1,7 @@
 ; 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)  {
@@ -604,7 +603,6 @@
 ; 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
 ;
@@ -616,7 +614,6 @@
 ; 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
@@ -631,7 +628,6 @@
 ; 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
Index: llvm/lib/Target/X86/X86FloatingPoint.cpp
===================================================================
--- llvm/lib/Target/X86/X86FloatingPoint.cpp
+++ llvm/lib/Target/X86/X86FloatingPoint.cpp
@@ -976,22 +976,27 @@
 //===----------------------------------------------------------------------===//
 
 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);
+    else
+      assert(MF->getFunction().getCallingConv() == CallingConv::X86_RegCall &&
+             "FP register use without regcall?");
 
-      STReturns |= 1 << R;
-    }
+    // Remove the operand so that later passes don't see it.
+    MI.RemoveOperand(i);
+    --i;
+    --e;
   }
 
   unsigned N = countTrailingOnes(STReturns);


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