[llvm-commits] [llvm] r168710 - in /llvm/trunk: lib/Target/X86/X86InstrInfo.cpp test/CodeGen/X86/fold-load-vec.ll

[Manman Ren]

Author: mren
Date: Tue Nov 27 12:09:26 2012
New Revision: 168710

URL: http://llvm.org/viewvc/llvm-project?rev=168710&view=rev
Log:
X86: do not fold load instructions such as [V]MOVS[S|D] to other instructions
when the destination register is wider than the memory load.

These load instructions load from m32 or m64 and set the upper bits to zero,
while the folded instructions may accept m128.

rdar://12721174

Added:
    llvm/trunk/test/CodeGen/X86/fold-load-vec.ll
Modified:
    llvm/trunk/lib/Target/X86/X86InstrInfo.cpp

Modified: llvm/trunk/lib/Target/X86/X86InstrInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86InstrInfo.cpp?rev=168710&r1=168709&r2=168710&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86InstrInfo.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86InstrInfo.cpp Tue Nov 27 12:09:26 2012
@@ -3982,6 +3982,21 @@
     break;
   }
   default: {
+    if ((LoadMI->getOpcode() == X86::MOVSSrm ||
+         LoadMI->getOpcode() == X86::VMOVSSrm) &&
+        MF.getRegInfo().getRegClass(LoadMI->getOperand(0).getReg())->getSize()
+          > 4)
+      // These instructions only load 32 bits, we can't fold them if the
+      // destination register is wider than 32 bits (4 bytes).
+      return NULL;
+    if ((LoadMI->getOpcode() == X86::MOVSDrm ||
+         LoadMI->getOpcode() == X86::VMOVSDrm) &&
+        MF.getRegInfo().getRegClass(LoadMI->getOperand(0).getReg())->getSize()
+          > 8)
+      // These instructions only load 64 bits, we can't fold them if the
+      // destination register is wider than 64 bits (8 bytes).
+      return NULL;
+
     // Folding a normal load. Just copy the load's address operands.
     unsigned NumOps = LoadMI->getDesc().getNumOperands();
     for (unsigned i = NumOps - X86::AddrNumOperands; i != NumOps; ++i)

Added: llvm/trunk/test/CodeGen/X86/fold-load-vec.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/fold-load-vec.ll?rev=168710&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/fold-load-vec.ll (added)
+++ llvm/trunk/test/CodeGen/X86/fold-load-vec.ll Tue Nov 27 12:09:26 2012
@@ -0,0 +1,39 @@
+; RUN: llc < %s -march=x86-64 -mcpu=corei7 -mattr=+sse41 | FileCheck %s
+
+; rdar://12721174
+; We should not fold movss into pshufd since pshufd expects m128 while movss
+; loads from m32.
+define void @sample_test(<4 x float>* %source, <2 x float>* %dest) nounwind {
+; CHECK: sample_test
+; CHECK: movss
+; CHECK: pshufd
+entry:
+  %source.addr = alloca <4 x float>*, align 8
+  %dest.addr = alloca <2 x float>*, align 8
+  %tmp = alloca <2 x float>, align 8
+  store <4 x float>* %source, <4 x float>** %source.addr, align 8
+  store <2 x float>* %dest, <2 x float>** %dest.addr, align 8
+  store <2 x float> zeroinitializer, <2 x float>* %tmp, align 8
+  %0 = load <4 x float>** %source.addr, align 8
+  %arrayidx = getelementptr inbounds <4 x float>* %0, i64 0
+  %1 = load <4 x float>* %arrayidx, align 16
+  %2 = extractelement <4 x float> %1, i32 0
+  %3 = load <2 x float>* %tmp, align 8
+  %4 = insertelement <2 x float> %3, float %2, i32 1
+  store <2 x float> %4, <2 x float>* %tmp, align 8
+  %5 = load <2 x float>* %tmp, align 8
+  %6 = load <2 x float>** %dest.addr, align 8
+  %arrayidx1 = getelementptr inbounds <2 x float>* %6, i64 0
+  store <2 x float> %5, <2 x float>* %arrayidx1, align 8
+  %7 = load <2 x float>** %dest.addr, align 8
+  %arrayidx2 = getelementptr inbounds <2 x float>* %7, i64 0
+  %8 = load <2 x float>* %arrayidx2, align 8
+  %vecext = extractelement <2 x float> %8, i32 0
+  %9 = load <2 x float>** %dest.addr, align 8
+  %arrayidx3 = getelementptr inbounds <2 x float>* %9, i64 0
+  %10 = load <2 x float>* %arrayidx3, align 8
+  %vecext4 = extractelement <2 x float> %10, i32 1
+  call void @ext(float %vecext, float %vecext4)
+  ret void
+}
+declare void @ext(float, float)