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llvm-mirror/test/Transforms/Inline/cgscc-update.ll
Chandler Carruth 69a65a83e5 [PM] Teach the inliner's call graph update to handle inserting new edges
when they are call edges at the leaf but may (transitively) be reached
via ref edges.

It turns out there is a simple rule: insert everything as a ref edge
which is a safe conservative default. Then we let the existing update
logic handle promoting some of those to call edges.

Note that it would be fairly cheap to make these call edges right away
if that is desirable by testing whether there is some existing call path
from the source to the target. It just seemed like slightly more
complexity in this code path that isn't strictly necessary. If anyone
feels strongly about handling this differently I'm happy to change it.

llvm-svn: 290649
2016-12-28 03:13:12 +00:00

185 lines
4.8 KiB
LLVM

; RUN: opt < %s -aa-pipeline=basic-aa -passes='cgscc(function-attrs,inline)' -S | FileCheck %s
; This test runs the inliner and the function attribute deduction. It ensures
; that when the inliner mutates the call graph it correctly updates the CGSCC
; iteration so that we can compute refined function attributes. In this way it
; is leveraging function attribute computation to observe correct call graph
; updates.
; Boring unknown external function call.
; CHECK: declare void @unknown()
declare void @unknown()
; Sanity check: this should get annotated as readnone.
; CHECK: Function Attrs: readnone
; CHECK-NEXT: declare void @readnone()
declare void @readnone() readnone
; The 'test1_' prefixed functions are designed to trigger forming a new direct
; call in the inlined body of the function. After that, we form a new SCC and
; using that can deduce precise function attrs.
; This function should no longer exist.
; CHECK-NOT: @test1_f()
define internal void @test1_f(void()* %p) {
entry:
call void %p()
ret void
}
; This function should have had 'readnone' deduced for its SCC.
; CHECK: Function Attrs: noinline readnone
; CHECK-NEXT: define void @test1_g()
define void @test1_g() noinline {
entry:
call void @test1_f(void()* @test1_h)
ret void
}
; This function should have had 'readnone' deduced for its SCC.
; CHECK: Function Attrs: noinline readnone
; CHECK-NEXT: define void @test1_h()
define void @test1_h() noinline {
entry:
call void @test1_g()
call void @readnone()
ret void
}
; The 'test2_' prefixed functions are designed to trigger forming a new direct
; call due to RAUW-ing the returned value of a called function into the caller.
; This too should form a new SCC which can then be reasoned about to compute
; precise function attrs.
; This function should no longer exist.
; CHECK-NOT: @test2_f()
define internal void()* @test2_f() {
entry:
ret void()* @test2_h
}
; This function should have had 'readnone' deduced for its SCC.
; CHECK: Function Attrs: noinline readnone
; CHECK-NEXT: define void @test2_g()
define void @test2_g() noinline {
entry:
%p = call void()* @test2_f()
call void %p()
ret void
}
; This function should have had 'readnone' deduced for its SCC.
; CHECK: Function Attrs: noinline readnone
; CHECK-NEXT: define void @test2_h()
define void @test2_h() noinline {
entry:
call void @test2_g()
call void @readnone()
ret void
}
; The 'test3_' prefixed functions are designed to inline in a way that causes
; call sites to become trivially dead during the middle of inlining callsites of
; a single function to make sure that the inliner does not get confused by this
; pattern.
; CHECK-NOT: @test3_maybe_unknown(
define internal void @test3_maybe_unknown(i1 %b) {
entry:
br i1 %b, label %then, label %exit
then:
call void @unknown()
br label %exit
exit:
ret void
}
; CHECK-NOT: @test3_f(
define internal i1 @test3_f() {
entry:
ret i1 false
}
; CHECK-NOT: @test3_g(
define internal i1 @test3_g(i1 %b) {
entry:
br i1 %b, label %then1, label %if2
then1:
call void @test3_maybe_unknown(i1 true)
br label %if2
if2:
%f = call i1 @test3_f()
br i1 %f, label %then2, label %exit
then2:
call void @test3_maybe_unknown(i1 true)
br label %exit
exit:
ret i1 false
}
; FIXME: Currently the inliner doesn't successfully mark this as readnone
; because while it simplifies trivially dead CFGs when inlining callees it
; doesn't simplify the caller's trivially dead CFG and so we end with a dead
; block calling @unknown.
; CHECK-NOT: Function Attrs: readnone
; CHECK: define void @test3_h()
define void @test3_h() {
entry:
%g = call i1 @test3_g(i1 false)
br i1 %g, label %then, label %exit
then:
call void @test3_maybe_unknown(i1 true)
br label %exit
exit:
call void @test3_maybe_unknown(i1 false)
ret void
}
; The 'test4_' prefixed functions are designed to trigger forming a new direct
; call in the inlined body of the function similar to 'test1_'. However, after
; that we continue to inline another edge of the graph forcing us to do a more
; interesting call graph update for the new call edge. Eventually, we still
; form a new SCC and should use that can deduce precise function attrs.
; This function should have had 'readnone' deduced for its SCC.
; CHECK: Function Attrs: noinline readnone
; CHECK-NEXT: define void @test4_f1()
define void @test4_f1() noinline {
entry:
call void @test4_h()
ret void
}
; CHECK-NOT: @test4_f2
define internal void @test4_f2() {
entry:
call void @test4_f1()
ret void
}
; CHECK-NOT: @test4_g
define internal void @test4_g(void()* %p) {
entry:
call void %p()
ret void
}
; This function should have had 'readnone' deduced for its SCC.
; CHECK: Function Attrs: noinline readnone
; CHECK-NEXT: define void @test4_h()
define void @test4_h() noinline {
entry:
call void @test4_g(void()* @test4_f2)
ret void
}