[llvm] r250960 - AMDGPU: Fix verifier error in SIFoldOperands

[Matt Arsenault via llvm-commits]

Author: arsenm
Date: Wed Oct 21 17:37:50 2015
New Revision: 250960

URL: http://llvm.org/viewvc/llvm-project?rev=250960&view=rev
Log:
AMDGPU: Fix verifier error in SIFoldOperands

There may be other use operands that also need their kill flags cleared.

This happens in a few tests when SIFoldOperands is moved after
PeepholeOptimizer.

PeepholeOptimizer rewrites cases that look like:
%vreg0 = ...
%vreg1 = COPY %vreg0
use %vreg1<kill>
%vreg2 = COPY %vreg0
use %vreg2<kill>

to use the earlier source to
%vreg0 = ...
use %vreg0
use %vreg0

Currently SIFoldOperands sees the copied registers, so there is
only one use. So far I haven't managed to come up with a test
that currently has multiple uses of a foldable VGPR -> VGPR copy.

Modified:
    llvm/trunk/lib/Target/AMDGPU/SIFoldOperands.cpp
    llvm/trunk/test/CodeGen/AMDGPU/si-instr-info-correct-implicit-operands.ll

Modified: llvm/trunk/lib/Target/AMDGPU/SIFoldOperands.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AMDGPU/SIFoldOperands.cpp?rev=250960&r1=250959&r2=250960&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AMDGPU/SIFoldOperands.cpp (original)
+++ llvm/trunk/lib/Target/AMDGPU/SIFoldOperands.cpp Wed Oct 21 17:37:50 2015
@@ -366,7 +366,10 @@ bool SIFoldOperands::runOnMachineFunctio
           // Clear kill flags.
           if (!Fold.isImm()) {
             assert(Fold.OpToFold && Fold.OpToFold->isReg());
-            Fold.OpToFold->setIsKill(false);
+            // FIXME: Probably shouldn't bother trying to fold if not an
+            // SGPR. PeepholeOptimizer can eliminate redundant VGPR->VGPR
+            // copies.
+            MRI.clearKillFlags(Fold.OpToFold->getReg());
           }
           DEBUG(dbgs() << "Folded source from " << MI << " into OpNo " <<
                 Fold.UseOpNo << " of " << *Fold.UseMI << '\n');

Modified: llvm/trunk/test/CodeGen/AMDGPU/si-instr-info-correct-implicit-operands.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AMDGPU/si-instr-info-correct-implicit-operands.ll?rev=250960&r1=250959&r2=250960&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AMDGPU/si-instr-info-correct-implicit-operands.ll (original)
+++ llvm/trunk/test/CodeGen/AMDGPU/si-instr-info-correct-implicit-operands.ll Wed Oct 21 17:37:50 2015
@@ -3,7 +3,7 @@
 ; register operands in the correct order when modifying the opcode of an
 ; instruction to V_ADD_I32_e32.
 
-; CHECK: %19 = V_ADD_I32_e32 killed %13, killed %12, implicit-def %vcc, implicit %exec
+; CHECK: %19 = V_ADD_I32_e32 %13, %12, implicit-def %vcc, implicit %exec
 
 define void @test(i32 addrspace(1)* %out, i32 addrspace(1)* %in) {
 entry: