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Transform this:

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%X = alloca ...
  %Y = alloca ...
    X == Y

into false.  This allows us to simplify some stuff in eon (and probably
many other C++ programs) where operator= was checking for self assignment.
Folding this allows us to SROA several additional structs.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17735 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2004-11-14 07:33:16 +00:00
parent 6739eae7ea
commit 711b3402aa
1 changed files with 6 additions and 4 deletions
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10
lib/Transforms/Scalar/InstructionCombining.cpp
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@@ -1870,12 +1870,14 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
if (isa<UndefValue>(Op1)) // X setcc undef -> undef if (isa<UndefValue>(Op1)) // X setcc undef -> undef
return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy)); return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy));
// setcc <global/alloca*>, 0 - Global/Stack value addresses are never null! // setcc <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
if (isa<ConstantPointerNull>(Op1) && // addresses never equal each other! We already know that Op0 != Op1.
(isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0))) if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
isa<ConstantPointerNull>(Op0)) &&
(isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
isa<ConstantPointerNull>(Op1)))
return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I))); return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
// setcc's with boolean values can always be turned into bitwise operations // setcc's with boolean values can always be turned into bitwise operations
if (Ty == Type::BoolTy) { if (Ty == Type::BoolTy) {
switch (I.getOpcode()) { switch (I.getOpcode()) {