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[Attributor] Use existing `returned` information better 

We can look through calls with `returned` argument attributes when we
collect subsuming positions. This allows us to get existing attributes
from more places.
This commit is contained in:
Johannes Doerfert 2020-02-19 23:39:57 -06:00
parent a801ee869d
commit f8ad735729
2 changed files with 26 additions and 9 deletions
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8
llvm/lib/Transforms/IPO/Attributor.cpp
View File

@ -645,6 +645,14 @@ SubsumingPositionIterator::SubsumingPositionIterator(const IRPosition &IRP) {
if (const Function *Callee = ICS.getCalledFunction()) {
IRPositions.emplace_back(IRPosition::returned(*Callee));
IRPositions.emplace_back(IRPosition::function(*Callee));
for (const Argument &Arg : Callee->args())
if (Arg.hasReturnedAttr()) {
IRPositions.emplace_back(
IRPosition::callsite_argument(ICS, Arg.getArgNo()));
IRPositions.emplace_back(
IRPosition::value(*ICS.getArgOperand(Arg.getArgNo())));
IRPositions.emplace_back(IRPosition::argument(Arg));
}
}
}
IRPositions.emplace_back(

27
llvm/test/Transforms/Attributor/returned.ll
View File

@ -771,26 +771,35 @@ define weak_odr i32 @non_exact_1(i32 %a) {
define weak_odr i32 @non_exact_2(i32 returned %a) {
ret i32 %a
}
define weak_odr i32* @non_exact_3(i32* align 32 returned %a) {
define weak_odr align 16 i32* @non_exact_3(i32* align 32 returned %a) {
ret i32* %a
}
define i32 @exact(i32* %a) {
define weak_odr align 16 i32* @non_exact_4(i32* align 32 %a) {
ret i32* %a
}
define i32 @exact(i32* align 8 %a, i32* align 8 %b) {
%c0 = call i32 @non_exact_0()
%c1 = call i32 @non_exact_1(i32 1)
%c2 = call i32 @non_exact_2(i32 2)
%c3 = call i32* @non_exact_3(i32* %a)
; We can use the information of the weak function non_exact_3 because it was
; given to us and not derived (the alignment of the returned argument).
; ATTRIBUTOR: %c4 = load i32, i32* %c3
%c4 = load i32, i32* %c3
%c4 = call i32* @non_exact_4(i32* %b)
; We can use the alignment information of the weak function non_exact_3 argument
; because it was given to us and not derived.
; ATTRIBUTOR: %c3l = load i32, i32* %c3, align 32
%c3l = load i32, i32* %c3
; We can use the return information of the weak function non_exact_4.
; ATTRIBUTOR: %c4l = load i32, i32* %c4, align 16
%c4l = load i32, i32* %c4
; FIXME: %c2 and %c3 should be replaced but not %c0 or %c1!
; ATTRIBUTOR: %add1 = add i32 %c0, %c1
; ATTRIBUTOR: %add2 = add i32 %add1, %c2
; ATTRIBUTOR: %add3 = add i32 %add2, %c4
; ATTRIBUTOR: %add3 = add i32 %add2, %c3l
; ATTRIBUTOR: %add4 = add i32 %add3, %c4l
%add1 = add i32 %c0, %c1
%add2 = add i32 %add1, %c2
%add3 = add i32 %add2, %c4
ret i32 %add3
%add3 = add i32 %add2, %c3l
%add4 = add i32 %add3, %c4l
ret i32 %add4
}
@G = external global i8