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Fix machine-cp by having it to check sub-register indicies. e.g.

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ecx = mov eax
al  = mov ch
The second copy is not a nop because the sub-indices of ecx,ch is not the
same of that of eax/al.

Re-enabled machine-cp.
PR11940


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151002 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2012-02-20 23:28:17 +00:00
parent acb6f5096f
commit 01b623c8c2
4 changed files with 105 additions and 4 deletions
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28
lib/CodeGen/MachineCopyPropagation.cpp
View File

@ -99,6 +99,31 @@ static bool NoInterveningSideEffect(const MachineInstr *CopyMI,
return true;
}
/// isNopCopy - Return true if the specified copy is really a nop. That is
/// if the source of the copy is the same of the definition of the copy that
/// supplied the source. If the source of the copy is a sub-register than it
/// must check the sub-indices match. e.g.
/// ecx = mov eax
/// al = mov cl
/// But not
/// ecx = mov eax
/// al = mov ch
static bool isNopCopy(MachineInstr *CopyMI, unsigned Def, unsigned Src,
const TargetRegisterInfo *TRI) {
unsigned SrcSrc = CopyMI->getOperand(1).getReg();
if (Def == SrcSrc)
return true;
if (TRI->isSubRegister(SrcSrc, Def)) {
unsigned SrcDef = CopyMI->getOperand(0).getReg();
unsigned SubIdx = TRI->getSubRegIndex(SrcSrc, Def);
if (!SubIdx)
return false;
return SubIdx == TRI->getSubRegIndex(SrcDef, Src);
}
return false;
}
bool MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
SmallSetVector<MachineInstr*, 8> MaybeDeadCopies; // Candidates for deletion
DenseMap<unsigned, MachineInstr*> AvailCopyMap; // Def -> available copies map
@ -122,10 +147,9 @@ bool MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
DenseMap<unsigned, MachineInstr*>::iterator CI = AvailCopyMap.find(Src);
if (CI != AvailCopyMap.end()) {
MachineInstr *CopyMI = CI->second;
unsigned SrcSrc = CopyMI->getOperand(1).getReg();
if (!ReservedRegs.test(Def) &&
(!ReservedRegs.test(Src) || NoInterveningSideEffect(CopyMI, MI)) &&
(SrcSrc == Def || TRI->isSubRegister(SrcSrc, Def))) {
isNopCopy(CopyMI, Def, Src, TRI)) {
// The two copies cancel out and the source of the first copy
// hasn't been overridden, eliminate the second one. e.g.
// %ECX<def> = COPY %EAX<kill>

2
lib/CodeGen/Passes.cpp
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@ -69,7 +69,7 @@ static cl::opt<bool> DisableLSR("disable-lsr", cl::Hidden,
static cl::opt<bool> DisableCGP("disable-cgp", cl::Hidden,
cl::desc("Disable Codegen Prepare"));
static cl::opt<bool> DisableCopyProp("disable-copyprop", cl::Hidden,
cl::desc("Disable Copy Propagation pass"), cl::init(true)); // PR11940
cl::desc("Disable Copy Propagation pass"));
static cl::opt<bool> PrintLSR("print-lsr-output", cl::Hidden,
cl::desc("Print LLVM IR produced by the loop-reduce pass"));
static cl::opt<bool> PrintISelInput("print-isel-input", cl::Hidden,

77
test/CodeGen/X86/2012-02-20-MachineCPBug.ll Normal file
View File

@ -0,0 +1,77 @@
; RUN: llc < %s -mtriple=i386-apple-macosx | FileCheck %s
; PR11940: Do not optimize away movb %al, %ch
%struct.APInt = type { i64* }
declare noalias i8* @calloc(i32, i32) nounwind
define void @bug(%struct.APInt* noalias nocapture sret %agg.result, %struct.APInt* nocapture %this, i32 %rotateAmt) nounwind align 2 {
entry:
; CHECK: bug:
%call = tail call i8* @calloc(i32 1, i32 32)
%call.i = tail call i8* @calloc(i32 1, i32 32) nounwind
%0 = bitcast i8* %call.i to i64*
%rem.i = and i32 %rotateAmt, 63
%div.i = lshr i32 %rotateAmt, 6
%cmp.i = icmp eq i32 %rem.i, 0
br i1 %cmp.i, label %for.cond.preheader.i, label %if.end.i
for.cond.preheader.i: ; preds = %entry
%sub.i = sub i32 4, %div.i
%cmp23.i = icmp eq i32 %div.i, 4
br i1 %cmp23.i, label %for.body9.lr.ph.i, label %for.body.lr.ph.i
for.body.lr.ph.i: ; preds = %for.cond.preheader.i
%pVal.i = getelementptr inbounds %struct.APInt* %this, i32 0, i32 0
%.pre5.i = load i64** %pVal.i, align 4
br label %for.body.i
for.body.i: ; preds = %for.body.i, %for.body.lr.ph.i
%i.04.i = phi i32 [ 0, %for.body.lr.ph.i ], [ %inc.i, %for.body.i ]
%add.i = add i32 %i.04.i, %div.i
%arrayidx.i = getelementptr inbounds i64* %.pre5.i, i32 %add.i
%1 = load i64* %arrayidx.i, align 4
%arrayidx3.i = getelementptr inbounds i64* %0, i32 %i.04.i
store i64 %1, i64* %arrayidx3.i, align 4
%inc.i = add i32 %i.04.i, 1
%cmp2.i = icmp ult i32 %inc.i, %sub.i
br i1 %cmp2.i, label %for.body.i, label %if.end.i
if.end.i: ; preds = %for.body.i, %entry
%cmp81.i = icmp eq i32 %div.i, 3
br i1 %cmp81.i, label %_ZNK5APInt4lshrEj.exit, label %for.body9.lr.ph.i
for.body9.lr.ph.i: ; preds = %if.end.i, %for.cond.preheader.i
%sub58.i = sub i32 3, %div.i
%pVal11.i = getelementptr inbounds %struct.APInt* %this, i32 0, i32 0
%sh_prom.i = zext i32 %rem.i to i64
%sub17.i = sub i32 64, %rem.i
%sh_prom18.i = zext i32 %sub17.i to i64
%.pre.i = load i64** %pVal11.i, align 4
br label %for.body9.i
for.body9.i: ; preds = %for.body9.i, %for.body9.lr.ph.i
; CHECK: %for.body9.i
; CHECK: movb %al, %ch
%i6.02.i = phi i32 [ 0, %for.body9.lr.ph.i ], [ %inc21.i, %for.body9.i ]
%add10.i = add i32 %i6.02.i, %div.i
%arrayidx12.i = getelementptr inbounds i64* %.pre.i, i32 %add10.i
%2 = load i64* %arrayidx12.i, align 4
%shr.i = lshr i64 %2, %sh_prom.i
%add14.i = add i32 %add10.i, 1
%arrayidx16.i = getelementptr inbounds i64* %.pre.i, i32 %add14.i
%3 = load i64* %arrayidx16.i, align 4
%shl.i = shl i64 %3, %sh_prom18.i
%or.i = or i64 %shl.i, %shr.i
%arrayidx19.i = getelementptr inbounds i64* %0, i32 %i6.02.i
store i64 %or.i, i64* %arrayidx19.i, align 4
%inc21.i = add i32 %i6.02.i, 1
%cmp8.i = icmp ult i32 %inc21.i, %sub58.i
br i1 %cmp8.i, label %for.body9.i, label %_ZNK5APInt4lshrEj.exit
_ZNK5APInt4lshrEj.exit: ; preds = %for.body9.i, %if.end.i
%call.i1 = tail call i8* @calloc(i32 1, i32 32) nounwind
%4 = getelementptr inbounds %struct.APInt* %agg.result, i32 0, i32 0
store i64* %0, i64** %4, align 4
ret void
}

2
test/CodeGen/X86/machine-cp.ll
View File

@ -1,4 +1,4 @@
; RUN: llc -mtriple=x86_64-apple-macosx -mcpu=nocona < %s -disable-copyprop=false | FileCheck %s
; RUN: llc -mtriple=x86_64-apple-macosx -mcpu=nocona < %s | FileCheck %s
; After tail duplication, two copies in an early exit BB can be cancelled out.
; rdar://10640363