[llvm] r240824 - AMDGPU: really don't commute REV opcodes if the target variant doesn't exist

[Marek Olsak]

Author: mareko
Date: Fri Jun 26 15:29:10 2015
New Revision: 240824

URL: http://llvm.org/viewvc/llvm-project?rev=240824&view=rev
Log:
AMDGPU: really don't commute REV opcodes if the target variant doesn't exist

If pseudoToMCOpcode failed, we would return the original opcode, so operands
would be swapped, but the instruction would remain the same.
It resulted in LSHLREV a, b ---> LSHLREV b, a.

This fixes Glamor text rendering and
piglit/arb_sample_shading-builtin-gl-sample-mask on VI.

This is a candidate for stable branches.

v2: the test was simplified by Tom Stellard

Added:
    llvm/trunk/test/CodeGen/AMDGPU/commute-shifts.ll
Modified:
    llvm/trunk/lib/Target/AMDGPU/SIInstrInfo.cpp
    llvm/trunk/lib/Target/AMDGPU/SIInstrInfo.h

Modified: llvm/trunk/lib/Target/AMDGPU/SIInstrInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AMDGPU/SIInstrInfo.cpp?rev=240824&r1=240823&r2=240824&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AMDGPU/SIInstrInfo.cpp (original)
+++ llvm/trunk/lib/Target/AMDGPU/SIInstrInfo.cpp Fri Jun 26 15:29:10 2015
@@ -440,22 +440,22 @@ SIInstrInfo::copyPhysReg(MachineBasicBlo
   }
 }
 
-unsigned SIInstrInfo::commuteOpcode(const MachineInstr &MI) const {
+int SIInstrInfo::commuteOpcode(const MachineInstr &MI) const {
   const unsigned Opcode = MI.getOpcode();
 
   int NewOpc;
 
   // Try to map original to commuted opcode
   NewOpc = AMDGPU::getCommuteRev(Opcode);
-  // Check if the commuted (REV) opcode exists on the target.
-  if (NewOpc != -1 && pseudoToMCOpcode(NewOpc) != -1)
-    return NewOpc;
+  if (NewOpc != -1)
+    // Check if the commuted (REV) opcode exists on the target.
+    return pseudoToMCOpcode(NewOpc) != -1 ? NewOpc : -1;
 
   // Try to map commuted to original opcode
   NewOpc = AMDGPU::getCommuteOrig(Opcode);
-  // Check if the original (non-REV) opcode exists on the target.
-  if (NewOpc != -1 && pseudoToMCOpcode(NewOpc) != -1)
-    return NewOpc;
+  if (NewOpc != -1)
+    // Check if the original (non-REV) opcode exists on the target.
+    return pseudoToMCOpcode(NewOpc) != -1 ? NewOpc : -1;
 
   return Opcode;
 }
@@ -771,6 +771,10 @@ MachineInstr *SIInstrInfo::commuteInstru
   if (MI->getNumOperands() < 3)
     return nullptr;
 
+  int CommutedOpcode = commuteOpcode(*MI);
+  if (CommutedOpcode == -1)
+    return nullptr;
+
   int Src0Idx = AMDGPU::getNamedOperandIdx(MI->getOpcode(),
                                            AMDGPU::OpName::src0);
   assert(Src0Idx != -1 && "Should always have src0 operand");
@@ -833,7 +837,7 @@ MachineInstr *SIInstrInfo::commuteInstru
   }
 
   if (MI)
-    MI->setDesc(get(commuteOpcode(*MI)));
+    MI->setDesc(get(CommutedOpcode));
 
   return MI;
 }

Modified: llvm/trunk/lib/Target/AMDGPU/SIInstrInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AMDGPU/SIInstrInfo.h?rev=240824&r1=240823&r2=240824&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AMDGPU/SIInstrInfo.h (original)
+++ llvm/trunk/lib/Target/AMDGPU/SIInstrInfo.h Fri Jun 26 15:29:10 2015
@@ -117,7 +117,7 @@ public:
   // register.  If there is no hardware instruction that can store to \p
   // DstRC, then AMDGPU::COPY is returned.
   unsigned getMovOpcode(const TargetRegisterClass *DstRC) const;
-  unsigned commuteOpcode(const MachineInstr &MI) const;
+  int commuteOpcode(const MachineInstr &MI) const;
 
   MachineInstr *commuteInstruction(MachineInstr *MI,
                                    bool NewMI = false) const override;

Added: llvm/trunk/test/CodeGen/AMDGPU/commute-shifts.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AMDGPU/commute-shifts.ll?rev=240824&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/AMDGPU/commute-shifts.ll (added)
+++ llvm/trunk/test/CodeGen/AMDGPU/commute-shifts.ll Fri Jun 26 15:29:10 2015
@@ -0,0 +1,33 @@
+; RUN: llc -march=amdgcn -mcpu=verde -verify-machineinstrs < %s | FileCheck -check-prefix=GCN -check-prefix=SI %s
+; RUN: llc -march=amdgcn -mcpu=tonga -verify-machineinstrs < %s | FileCheck -check-prefix=GCN -check-prefix=VI %s
+
+; GCN-LABEL: {{^}}main:
+; SI: v_lshl_b32_e32 v{{[0-9]+}}, 1, v{{[0-9]+}}
+; VI: v_lshlrev_b32_e64 v{{[0-9]+}}, v{{[0-9]+}}, 1
+
+define void @main() #0 {
+main_body:
+  %0 = fptosi float undef to i32
+  %1 = call <4 x i32> @llvm.SI.imageload.v4i32(<4 x i32> undef, <32 x i8> undef, i32 2)
+  %2 = extractelement <4 x i32> %1, i32 0
+  %3 = and i32 %0, 7
+  %4 = shl i32 1, %3
+  %5 = and i32 %2, %4
+  %6 = icmp eq i32 %5, 0
+  %.10 = select i1 %6, float 0.000000e+00, float undef
+  %7 = call i32 @llvm.SI.packf16(float undef, float %.10)
+  %8 = bitcast i32 %7 to float
+  call void @llvm.SI.export(i32 15, i32 1, i32 1, i32 0, i32 1, float undef, float %8, float undef, float %8)
+  ret void
+}
+
+; Function Attrs: nounwind readnone
+declare <4 x i32> @llvm.SI.imageload.v4i32(<4 x i32>, <32 x i8>, i32) #1
+
+; Function Attrs: nounwind readnone
+declare i32 @llvm.SI.packf16(float, float) #1
+
+declare void @llvm.SI.export(i32, i32, i32, i32, i32, float, float, float, float)
+
+attributes #0 = { "ShaderType"="0" "enable-no-nans-fp-math"="true" }
+attributes #1 = { nounwind readnone }