[llvm-commits] [llvm] r72369 - in /llvm/trunk: lib/Transforms/Scalar/IndVarSimplify.cpp test/Transforms/IndVarSimplify/lftr-other-uses.ll

[Dan Gohman]

Author: djg
Date: Sun May 24 14:11:38 2009
New Revision: 72369

URL: http://llvm.org/viewvc/llvm-project?rev=72369&view=rev
Log:
When rewriting the loop exit test with the canonical induction variable,
leave the original comparison in place if it has other uses, since the
other uses won't be dominated by the new comparison instruction.

Added:
    llvm/trunk/test/Transforms/IndVarSimplify/lftr-other-uses.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp?rev=72369&r1=72368&r2=72369&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp Sun May 24 14:11:38 2009
@@ -187,7 +187,12 @@
   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;

Added: llvm/trunk/test/Transforms/IndVarSimplify/lftr-other-uses.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/lftr-other-uses.ll?rev=72369&view=auto

==============================================================================
--- llvm/trunk/test/Transforms/IndVarSimplify/lftr-other-uses.ll (added)
+++ llvm/trunk/test/Transforms/IndVarSimplify/lftr-other-uses.ll Sun May 24 14:11:38 2009
@@ -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
+}