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Fix a bug in my checkin from last night that caused miscompilations of
186.crafty, fhourstones and 132.ijpeg. Bugpoint makes really nasty miscompilations embarassingly easy to find. It narrowed it down to the instcombiner and this testcase (from fhourstones): bool %l7153_l4706_htstat_loopentry_2E_4_no_exit_2E_4(int* %i, [32 x int]* %works, int* %tmp.98.out) { newFuncRoot: %tmp.96 = load int* %i ; <int> [#uses=1] %tmp.97 = getelementptr [32 x int]* %works, long 0, int %tmp.96 ; <int*> [#uses=1] %tmp.98 = load int* %tmp.97 ; <int> [#uses=2] %tmp.99 = load int* %i ; <int> [#uses=1] %tmp.100 = and int %tmp.99, 7 ; <int> [#uses=1] %tmp.101 = seteq int %tmp.100, 7 ; <bool> [#uses=2] %tmp.102 = cast bool %tmp.101 to int ; <int> [#uses=0] br bool %tmp.101, label %codeRepl4.exitStub, label %codeRepl3.exitStub codeRepl4.exitStub: ; preds = %newFuncRoot store int %tmp.98, int* %tmp.98.out ret bool true codeRepl3.exitStub: ; preds = %newFuncRoot store int %tmp.98, int* %tmp.98.out ret bool false } ... which only has one combination performed on it: $ llvm-as < t.ll | opt -instcombine -debug | llvm-dis IC: Old = %tmp.101 = seteq int %tmp.100, 7 ; <bool> [#uses=1] New = setne int %tmp.100, 0 ; <bool>:<badref> [#uses=0] IC: MOD = br bool %tmp.101, label %codeRepl3.exitStub, label %codeRepl4.exitStub IC: MOD = %tmp.97 = getelementptr [32 x int]* %works, uint 0, int %tmp.96 ; <int*> [#uses=1] It doesn't get much better than this. :) llvm-svn: 14109
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@ -1582,14 +1582,10 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
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return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
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// If we have ((X & C) == C), turn it into ((X & C) != 0).
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if (CI == BOC) {
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// Don't infinite loop if C is null and the & isn't folded yet.
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if (CI->isNullValue())
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return ReplaceInstUsesWith(I, ConstantBool::get(!isSetNE));
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if (CI == BOC && isOneBitSet(CI))
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return new SetCondInst(isSetNE ? Instruction::SetEQ :
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Instruction::SetNE, Op0,
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Constant::getNullValue(CI->getType()));
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}
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// Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
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// to be a signed value as appropriate.
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