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Remove an orthogonal transformation of the selection condition from my most recent submission.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45169 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Christopher Lamb 2007-12-18 20:30:28 +00:00
parent fd52711675
commit fd8b1fd7f6
2 changed files with 3 additions and 40 deletions
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32
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -2131,9 +2131,6 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
}
}
// add (select (icmp 0 (sub m A)) X Y) A ->
// add (select (icmp A m) X Y) A
//
// add (select X 0 (sub n A)) A ->
// select X A n
{
@ -2147,27 +2144,6 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
Value *TV = SI->getTrueValue();
Value *FV = SI->getFalseValue();
Value *A;
// Can we fold the add into the argument of the compare?
Value *Cond = SI->getCondition();
if (ICmpInst *IC = dyn_cast<ICmpInst>(Cond)) {
Value *ICOp0 = IC->getOperand(0);
Value *ICOp1 = IC->getOperand(1);
ConstantInt *C3, *C4;
// Check both arguments of the compare for a matching subtract.
if (match(ICOp0, m_ConstantInt(C3)) && C3->getValue() == 0 &&
match(ICOp1, m_Sub(m_ConstantInt(C4), m_Value(A))) &&
A == Other) {
// We managed to fold the add into the RHS of the select condition.
Cond = new ICmpInst(IC->getPredicate(), A, C4, "asis", SI);
} else if (match(ICOp1, m_ConstantInt(C3)) && C3->getValue() == 0 &&
match(ICOp0, m_Sub(m_ConstantInt(C4), m_Value(A))) &&
A == Other) {
// We managed to fold the add into the LHS of the select condition.
Cond = new ICmpInst(IC->getPredicate(), C4, A, "asis", SI);
}
}
// Can we fold the add into the argument of the select?
// We check both true and false select arguments for a matching subtract.
@ -2177,17 +2153,13 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
A == Other) {
// We managed to fold the add into the true select value,
// picking up a simplified condition, if available.
return new SelectInst(Cond, C2, A, "adselsub");
return new SelectInst(SI->getCondition(), C2, A);
} else if (match(TV, m_ConstantInt(C1)) && C1->getValue() == 0 &&
match(FV, m_Sub(m_ConstantInt(C2), m_Value(A))) &&
A == Other) {
// We managed to fold the add into the false select value,
// picking up a simplified condition, if available.
return new SelectInst(Cond, A, C2, "adselsub");
} else if (Cond != SI->getCondition()) {
// We only managed to fold the add into the select condition.
SI->setOperand(0, Cond);
Changed = true;
return new SelectInst(SI->getCondition(), A, C2);
}
}
}

11
test/Transforms/InstCombine/2007-12-18-AddSelCmpSub.ll
View File

@ -1,4 +1,4 @@
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep {sub}
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {add} | count 1
define i32 @foo(i32 %a) {
entry:
@ -19,15 +19,6 @@ entry:
ret i32 %tmp12
}
define i32 @baz(i32 %a) {
entry:
%tmp15 = sub i32 99, %a ; <i32> [#uses=1]
%tmp16 = icmp slt i32 %tmp15, 0 ; <i1> [#uses=1]
%smax = select i1 %tmp16, i32 0, i32 42 ; <i32> [#uses=1]
%tmp12 = add i32 %smax, %a ; <i32> [#uses=1]
ret i32 %tmp12
}
define i32 @fun(i32 %a) {
entry:
%tmp15 = sub i32 99, %a ; <i32> [#uses=1]