[llvm] r231243 - [X86][FastISel] Simplify the logic in method X86SelectSIToFP.

[Andrea Di Biagio]

Author: adibiagio
Date: Wed Mar  4 08:23:25 2015
New Revision: 231243

URL: http://llvm.org/viewvc/llvm-project?rev=231243&view=rev
Log:
[X86][FastISel] Simplify the logic in method X86SelectSIToFP.

The target-independent selection algorithm in FastISel already knows how
to select a SINT_TO_FP if the target is SSE but not AVX.

On targets that have SSE but not AVX, the tablegen'd 'fastEmit' functions
for ISD::SINT_TO_FP know how to select instruction X86::CVTSI2SSrr
(for an i32 to f32 conversion) and X86::CVTSI2SDrr (for an i32 to f64
conversion).

This patch simplifies the logic in method X86SelectSIToFP knowing that
the code would not be reachable if the subtarget doesn't have AVX.
No functional change intended.

Modified:
    llvm/trunk/lib/Target/X86/X86FastISel.cpp
    llvm/trunk/test/CodeGen/X86/fast-isel-int-float-conversion.ll

Modified: llvm/trunk/lib/Target/X86/X86FastISel.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86FastISel.cpp?rev=231243&r1=231242&r2=231243&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86FastISel.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86FastISel.cpp Wed Mar  4 08:23:25 2015
@@ -2015,38 +2015,30 @@ bool X86FastISel::X86SelectSIToFP(const
   if (OpReg == 0)
     return false;
 
-  bool HasAVX = Subtarget->hasAVX();
   const TargetRegisterClass *RC = nullptr;
   unsigned Opcode;
 
-  if (I->getType()->isDoubleTy() && X86ScalarSSEf64) {
+  if (I->getType()->isDoubleTy()) {
     // sitofp int -> double
-    Opcode = HasAVX ? X86::VCVTSI2SDrr : X86::CVTSI2SDrr;
+    Opcode = X86::VCVTSI2SDrr;
     RC = &X86::FR64RegClass;
-  } else if (I->getType()->isFloatTy() && X86ScalarSSEf32) {
+  } else if (I->getType()->isFloatTy()) {
     // sitofp int -> float
-    Opcode = HasAVX ? X86::VCVTSI2SSrr : X86::CVTSI2SSrr;
+    Opcode = X86::VCVTSI2SSrr;
     RC = &X86::FR32RegClass;
   } else
     return false;
 
+  // The target-independent selection algorithm in FastISel already knows how
+  // to select a SINT_TO_FP if the target is SSE but not AVX. This code is only
+  // reachable if the subtarget has AVX.
+  assert(Subtarget->hasAVX() && "Expected a subtarget with AVX!");
 
-  unsigned ImplicitDefReg = 0;
-  if (HasAVX) {
-    ImplicitDefReg = createResultReg(RC);
-    BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
-            TII.get(TargetOpcode::IMPLICIT_DEF), ImplicitDefReg);
-  }
-
-  const MCInstrDesc &II = TII.get(Opcode);
-  OpReg = constrainOperandRegClass(II, OpReg, (HasAVX ? 2 : 1));
-  
-  unsigned ResultReg = createResultReg(RC);
-  MachineInstrBuilder MIB;
-  MIB = BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, II, ResultReg);
-  if (ImplicitDefReg)
-    MIB.addReg(ImplicitDefReg, RegState::Kill);
-  MIB.addReg(OpReg);
+  unsigned ImplicitDefReg = createResultReg(RC);
+  BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
+          TII.get(TargetOpcode::IMPLICIT_DEF), ImplicitDefReg);
+  unsigned ResultReg =
+      fastEmitInst_rr(Opcode, RC, ImplicitDefReg, true, OpReg, false);
   updateValueMap(I, ResultReg);
   return true;
 }

Modified: llvm/trunk/test/CodeGen/X86/fast-isel-int-float-conversion.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/fast-isel-int-float-conversion.ll?rev=231243&r1=231242&r2=231243&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/fast-isel-int-float-conversion.ll (original)
+++ llvm/trunk/test/CodeGen/X86/fast-isel-int-float-conversion.ll Wed Mar  4 08:23:25 2015
@@ -1,5 +1,5 @@
-; RUN: llc -mtriple=x86_64-unknown-unknown -mcpu=generic -mattr=+sse2 -O0 --fast-isel-abort=1 < %s | FileCheck %s --check-prefix=ALL --check-prefix=SSE2
-; RUN: llc -mtriple=x86_64-unknown-unknown -mcpu=generic -mattr=+avx -O0 --fast-isel-abort=1 < %s | FileCheck %s --check-prefix=ALL --check-prefix=AVX
+; RUN: llc -mtriple=x86_64-unknown-unknown -mcpu=generic -mattr=+sse2 -fast-isel --fast-isel-abort=1 < %s | FileCheck %s --check-prefix=ALL --check-prefix=SSE2
+; RUN: llc -mtriple=x86_64-unknown-unknown -mcpu=generic -mattr=+avx -fast-isel --fast-isel-abort=1 < %s | FileCheck %s --check-prefix=ALL --check-prefix=AVX
 
 
 define double @int_to_double_rr(i32 %a) {