Inliner fails to simplify inlined function based on known callsite attributes

[davidbolvansky]

caller3 example from tests:

llvm-project/llvm/test/Transforms/Inline/nonnull.ll

Line 75 in ca42cd3

define void @caller3(ptr %arg) {

It should be simplified to "call bar", but currently Inliner fails to do so (ignores SimplifiedValues in this case?)

[davidbolvansky]

cc @aeubanks @mtrofin

[aeubanks]

Ultimately the value that the SimplifyInstruction call in the inliner sees is just the Argument ptr %arg, it's hard to attach the call-site nonnull to the value somehow when inlining. but perhaps we could add a nonnull assume when inlining, which should fix this

for example, inlining the following loses the nonnull

declare void @h(ptr %p)

define void @f(ptr %p) {
	call void @g(ptr nonnull %p)
	ret void
}

define void @g(ptr %p) {
	call void @h(ptr %p)
	ret void
}

[davidbolvansky]

Yeah, assumes may work well here.

I was wondering if we could reuse built map SimplifiedValues from InlineCost CallAnalyzer and use it to simplify instructions..

[mtrofin]

@kazutakahirata

[davidbolvansky]

Proposal:
https://reviews.llvm.org/D147704