[llvm] r199282 - PR 18466: Fix ARM Pseudo Expansion

[Weiming Zhao]

Author: weimingz
Date: Tue Jan 14 19:32:12 2014
New Revision: 199282

URL: http://llvm.org/viewvc/llvm-project?rev=199282&view=rev
Log:
PR 18466: Fix ARM Pseudo Expansion

When expanding neon pseudo stores, it may miss the implicit uses of sub
regs, which may cause post RA scheduler reorder instructions that
breakes anti dependency.

For example:
  VST1d64QPseudo %R0<kill>, 16, %Q9_Q10, pred:14, pred:%noreg
  will be expanded to
    VST1d64Q %R0<kill>, 16, %D18, pred:14, pred:%noreg;

An instruction that defines %D20 may be scheduled before the store by
mistake.

This patches adds implicit uses for such case. For the example above, it
emits:
  VST1d64Q %R0<kill>, 8, %D18, pred:14, pred:%noreg, %Q9_Q10<imp-use>

Added:
    llvm/trunk/test/CodeGen/ARM/2014-01-09-pseudo_expand_implicit_reg.ll
Modified:
    llvm/trunk/lib/Target/ARM/ARMExpandPseudoInsts.cpp

Modified: llvm/trunk/lib/Target/ARM/ARMExpandPseudoInsts.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMExpandPseudoInsts.cpp?rev=199282&r1=199281&r2=199282&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMExpandPseudoInsts.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMExpandPseudoInsts.cpp Tue Jan 14 19:32:12 2014
@@ -479,6 +479,8 @@ void ARMExpandPseudo::ExpandVST(MachineB
 
   if (SrcIsKill && !SrcIsUndef) // Add an implicit kill for the super-reg.
     MIB->addRegisterKilled(SrcReg, TRI, true);
+  else if (!SrcIsUndef)
+    MIB.addReg(SrcReg, RegState::Implicit); // Add implicit uses for src reg.
   TransferImpOps(MI, MIB, MIB);
 
   // Transfer memoperands.
@@ -604,8 +606,8 @@ void ARMExpandPseudo::ExpandVTBL(Machine
   MIB.addOperand(MI.getOperand(OpIdx++));
   MIB.addOperand(MI.getOperand(OpIdx++));
 
-  if (SrcIsKill)  // Add an implicit kill for the super-reg.
-    MIB->addRegisterKilled(SrcReg, TRI, true);
+  // Add an implicit kill and use for the super-reg.
+  MIB.addReg(SrcReg, RegState::Implicit | getKillRegState(SrcIsKill));
   TransferImpOps(MI, MIB, MIB);
   MI.eraseFromParent();
 }

Added: llvm/trunk/test/CodeGen/ARM/2014-01-09-pseudo_expand_implicit_reg.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/2014-01-09-pseudo_expand_implicit_reg.ll?rev=199282&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/2014-01-09-pseudo_expand_implicit_reg.ll (added)
+++ llvm/trunk/test/CodeGen/ARM/2014-01-09-pseudo_expand_implicit_reg.ll Tue Jan 14 19:32:12 2014
@@ -0,0 +1,55 @@
+; RUN: llc < %s -march=arm -mattr=+neon -print-before=post-RA-sched  > %t 2>&1 && FileCheck < %t %s
+
+define void @vst(i8* %m, [4 x i64] %v) {
+entry:
+; CHECK: vst:
+; CHECK: VST1d64Q %R{{[0-9]+}}<kill>, 8, %D{{[0-9]+}}, pred:14, pred:%noreg, %Q{{[0-9]+}}_Q{{[0-9]+}}<imp-use>
+
+  %v0 = extractvalue [4 x i64] %v, 0
+  %v1 = extractvalue [4 x i64] %v, 1
+  %v2 = extractvalue [4 x i64] %v, 2
+  %v3 = extractvalue [4 x i64] %v, 3
+
+  %t0 = bitcast i64 %v0 to <8 x i8>
+  %t1 = bitcast i64 %v1 to <8 x i8>
+  %t2 = bitcast i64 %v2 to <8 x i8>
+  %t3 = bitcast i64 %v3 to <8 x i8>
+
+  %s0 = bitcast <8 x i8> %t0 to <1 x i64>
+  %s1 = bitcast <8 x i8> %t1 to <1 x i64>
+  %s2 = bitcast <8 x i8> %t2 to <1 x i64>
+  %s3 = bitcast <8 x i8> %t3 to <1 x i64>
+
+  %tmp0 = bitcast <1 x i64> %s2 to i64
+  %tmp1 = bitcast <1 x i64> %s3 to i64
+
+  %n0 = insertelement <2 x i64> undef, i64 %tmp0, i32 0
+  %n1 = insertelement <2 x i64> %n0, i64 %tmp1, i32 1
+
+  call void @llvm.arm.neon.vst4.v1i64(i8* %m, <1 x i64> %s0, <1 x i64> %s1, <1 x i64> %s2, <1 x i64> %s3, i32 8)
+
+  call void @bar(<2 x i64> %n1)
+
+  ret void
+}
+
+%struct.__neon_int8x8x4_t = type { <8 x i8>,  <8 x i8>,  <8 x i8>, <8 x i8> }
+define <8 x i8> @vtbx4(<8 x i8>* %A, %struct.__neon_int8x8x4_t* %B, <8 x i8>* %C) nounwind {
+; CHECK: vtbx4:
+; CHECK: VTBX4 {{.*}}, pred:14, pred:%noreg, %Q{{[0-9]+}}_Q{{[0-9]+}}<imp-use>
+	%tmp1 = load <8 x i8>* %A
+	%tmp2 = load %struct.__neon_int8x8x4_t* %B
+        %tmp3 = extractvalue %struct.__neon_int8x8x4_t %tmp2, 0
+        %tmp4 = extractvalue %struct.__neon_int8x8x4_t %tmp2, 1
+        %tmp5 = extractvalue %struct.__neon_int8x8x4_t %tmp2, 2
+        %tmp6 = extractvalue %struct.__neon_int8x8x4_t %tmp2, 3
+	%tmp7 = load <8 x i8>* %C
+	%tmp8 = call <8 x i8> @llvm.arm.neon.vtbx4(<8 x i8> %tmp1, <8 x i8> %tmp3, <8 x i8> %tmp4, <8 x i8> %tmp5, <8 x i8> %tmp6, <8 x i8> %tmp7)
+  call void @bar2(%struct.__neon_int8x8x4_t %tmp2, <8 x i8> %tmp8)
+	ret <8 x i8> %tmp8
+}
+
+declare void @llvm.arm.neon.vst4.v1i64(i8*, <1 x i64>, <1 x i64>, <1 x i64>, <1 x i64>, i32)
+declare <8 x i8>  @llvm.arm.neon.vtbx4(<8 x i8>, <8 x i8>, <8 x i8>, <8 x i8>, <8 x i8>, <8 x i8>) nounwind readnone
+declare void @bar2(%struct.__neon_int8x8x4_t, <8 x i8>)
+declare void @bar(<2 x i64> %arg)