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indvars -disable-iv-rewrite: handle cloning binary operators that cannot overflow.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134177 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2011-06-30 19:02:17 +00:00
parent 16f9924000
commit 6e0ce24e0c
2 changed files with 45 additions and 7 deletions
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10
lib/Transforms/Scalar/IndVarSimplify.cpp
View File

@ -659,9 +659,11 @@ Instruction *WidenIV::CloneIVUser(Instruction *NarrowUse,
LHS, RHS,
NarrowBO->getName());
Builder.Insert(WideBO);
if (NarrowBO->hasNoUnsignedWrap()) WideBO->setHasNoUnsignedWrap();
if (NarrowBO->hasNoSignedWrap()) WideBO->setHasNoSignedWrap();
if (const OverflowingBinaryOperator *OBO =
dyn_cast<OverflowingBinaryOperator>(NarrowBO)) {
if (OBO->hasNoUnsignedWrap()) WideBO->setHasNoUnsignedWrap();
if (OBO->hasNoSignedWrap()) WideBO->setHasNoSignedWrap();
}
return WideBO;
}
llvm_unreachable(0);
@ -1121,6 +1123,8 @@ void IndVarSimplify::SimplifyIVUsersNoRewrite(Loop *L, SCEVExpander &Rewriter) {
while (!SimpleIVUsers.empty()) {
Instruction *UseInst, *Operand;
tie(UseInst, Operand) = SimpleIVUsers.pop_back_val();
// Bypass back edges to avoid extra work.
if (UseInst == CurrIV) continue;
if (EliminateIVUser(UseInst, Operand)) {
pushIVUsers(Operand, Simplified, SimpleIVUsers);

42
test/Transforms/IndVarSimplify/no-iv-rewrite.ll
View File

@ -160,6 +160,8 @@ define void @maxvisitor(i32 %limit, i32* %base) nounwind {
entry:
br label %loop
; Test inserting a truncate at a phi use.
;
; CHECK: loop:
; CHECK: phi i64
; CHECK: trunc
@ -189,14 +191,17 @@ exit:
ret void
}
; CHECK: loop:
; CHECK: phi i32
; CHECK-NOT: phi
; CHECK: exit:
define void @identityphi(i32 %limit) nounwind {
entry:
br label %loop
; Test an edge case of removing an identity phi that directly feeds
; back to the loop iv.
;
; CHECK: loop:
; CHECK: phi i32
; CHECK-NOT: phi
; CHECK: exit:
loop:
%iv = phi i32 [ 0, %entry], [ %iv.next, %control ]
br i1 undef, label %if.then, label %control
@ -212,3 +217,32 @@ control:
exit:
ret void
}
define i64 @cloneOr(i32 %limit, i64* %base) nounwind {
entry:
; ensure that the loop can't overflow
%halfLim = ashr i32 %limit, 2
br label %loop
; Test cloning an or, which is not an OverflowBinaryOperator.
;
; CHECK: loop:
; CHECK: phi i64
; CHECK-NOT: sext
; CHECK: or i64
; CHECK: exit:
loop:
%iv = phi i32 [ 0, %entry], [ %iv.next, %loop ]
%t1 = sext i32 %iv to i64
%adr = getelementptr i64* %base, i64 %t1
%val = load i64* %adr
%t2 = or i32 %iv, 1
%t3 = sext i32 %t2 to i64
%iv.next = add i32 %iv, 2
%cmp = icmp slt i32 %iv.next, %halfLim
br i1 %cmp, label %loop, label %exit
exit:
%result = and i64 %val, %t3
ret i64 %result
}