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When rewriting the loop exit test with the canonical induction variable,

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leave the original comparison in place if it has other uses, since the
other uses won't be dominated by the new comparison instruction.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72369 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2009-05-24 19:11:38 +00:00
parent fb5a3419f3
commit 95bdbfa066
2 changed files with 42 additions and 1 deletions
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7
lib/Transforms/Scalar/IndVarSimplify.cpp
View File

@ -187,7 +187,12 @@ ICmpInst *IndVarSimplify::LinearFunctionTestReplace(Loop *L,
ICmpInst *Cond = new ICmpInst(Opcode, CmpIndVar, ExitCnt, "exitcond", BI);
Instruction *OrigCond = cast<Instruction>(BI->getCondition());
OrigCond->replaceAllUsesWith(Cond);
// It's tempting to use replaceAllUsesWith here to fully replace the old
// comparison, but that's not immediately safe, since users of the old
// comparison may not be dominated by the new comparison. Instead, just
// update the branch to use the new comparison; in the common case this
// will make old comparison dead.
BI->setCondition(Cond);
RecursivelyDeleteTriviallyDeadInstructions(OrigCond);
++NumLFTR;

36
test/Transforms/IndVarSimplify/lftr-other-uses.ll Normal file
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@ -0,0 +1,36 @@
; RUN: llvm-as < %s | opt -indvars -disable-output
; Don't RAUW the loop's original comparison instruction if it has
; other uses which aren't dominated by the new comparison instruction.
%struct.DecRefPicMarking_s = type { i32, i32, i32, i32, i32, %struct.DecRefPicMarking_s* }
%struct.datapartition = type { %typedef.Bitstream*, %typedef.DecodingEnvironment, i32 (%struct.syntaxelement*, %struct.img_par*, %struct.inp_par*, %struct.datapartition*)* }
%struct.img_par = type { i32, i32, i32, i32, i32*, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, [16 x [16 x i16]], [6 x [32 x i32]], [16 x [16 x i32]], [4 x [12 x [4 x [4 x i32]]]], [16 x i32], i32**, i32*, i32***, i32**, i32, i32, i32, i32, %typedef.Slice*, %struct.macroblock*, i32, i32, i32, i32, i32, i32, i32**, %struct.DecRefPicMarking_s*, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, [3 x i32], i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32***, i32***, i32****, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, %struct.timeb, %struct.timeb, i32, i32, i32, i32, i32, i32, i32, i32 }
%struct.inp_par = type { [100 x i8], [100 x i8], [100 x i8], i32, i32, i32, i32, i32, i32, i32 }
%struct.macroblock = type { i32, i32, i32, %struct.macroblock*, %struct.macroblock*, i32, [2 x [4 x [4 x [2 x i32]]]], i32, i64, i64, i32, i32, [4 x i32], [4 x i32], i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 }
%struct.syntaxelement = type { i32, i32, i32, i32, i32, i32, i32, i32, void (i32, i32, i32*, i32*)*, void (%struct.syntaxelement*, %struct.inp_par*, %struct.img_par*, %typedef.DecodingEnvironment*)* }
%struct.timeb = type { i32, i16, i16, i16 }
%typedef.BiContextType = type { i16, i8 }
%typedef.Bitstream = type { i32, i32, i32, i32, i8*, i32 }
%typedef.DecodingEnvironment = type { i32, i32, i32, i32, i32, i8*, i32* }
%typedef.MotionInfoContexts = type { [4 x [11 x %typedef.BiContextType]], [2 x [9 x %typedef.BiContextType]], [2 x [10 x %typedef.BiContextType]], [2 x [6 x %typedef.BiContextType]], [4 x %typedef.BiContextType], [4 x %typedef.BiContextType], [3 x %typedef.BiContextType] }
%typedef.Slice = type { i32, i32, i32, i32, i32, i32, i32, i32, i32, %struct.datapartition*, %typedef.MotionInfoContexts*, %typedef.TextureInfoContexts*, i32, i32*, i32*, i32*, i32, i32*, i32*, i32*, i32 (%struct.img_par*, %struct.inp_par*)*, i32, i32, i32, i32 }
%typedef.TextureInfoContexts = type { [2 x %typedef.BiContextType], [4 x %typedef.BiContextType], [3 x [4 x %typedef.BiContextType]], [10 x [4 x %typedef.BiContextType]], [10 x [15 x %typedef.BiContextType]], [10 x [15 x %typedef.BiContextType]], [10 x [5 x %typedef.BiContextType]], [10 x [5 x %typedef.BiContextType]], [10 x [15 x %typedef.BiContextType]], [10 x [15 x %typedef.BiContextType]] }
define void @readCBP_CABAC(%struct.syntaxelement* %se, %struct.inp_par* %inp, %struct.img_par* %img.1, %typedef.DecodingEnvironment* %dep_dp) {
entry:
br label %loopentry.0
loopentry.0: ; preds = %loopentry.1, %entry
%mb_y.0 = phi i32 [ 0, %entry ], [ %tmp.152, %loopentry.1 ] ; <i32> [#uses=2]
%tmp.14 = icmp sle i32 %mb_y.0, 3 ; <i1> [#uses=2]
%tmp.15 = zext i1 %tmp.14 to i32 ; <i32> [#uses=0]
br i1 %tmp.14, label %loopentry.1, label %loopexit.0
loopentry.1: ; preds = %loopentry.0
%tmp.152 = add i32 %mb_y.0, 2 ; <i32> [#uses=1]
br label %loopentry.0
loopexit.0: ; preds = %loopentry.0
unreachable
}