491dd2711f
``` // The legacy PM CGPassManager discovers SCCs this way: for function in the source order tarjanSCC(function) // While the new PM CGSCCPassManager does: for function in the reversed source order [1] discover a reference graph SCC build call graph SCCs inside the reference graph SCC ``` In the common cases, reference graph ~= call graph, the new PM order is undesired because for `a | b | c` (3 independent functions), the new PM will process them in the reversed order: c, b, a. If `a <-> b <-> c`, we can see that `-print-after-all` will report the sole SCC as `scc: (c, b, a)`. This patch corrects the iteration order. The discovered SCC order will match the legacy PM in the common cases. For some tests (`Transforms/Inline/cgscc-*.ll` and `unittests/Analysis/CGSCCPassManagerTest.cpp`), the behaviors are dependent on the SCC discovery order and there are too many check lines for the particular order. This patch simply reverses the function order to avoid changing too many check lines. Differential Revision: https://reviews.llvm.org/D90566
233 lines
7.7 KiB
LLVM
233 lines
7.7 KiB
LLVM
; This test contains extremely tricky call graph structures for the inliner to
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; handle correctly. They form cycles where the inliner introduces code that is
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; immediately or can eventually be transformed back into the original code. And
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; each step changes the call graph and so will trigger iteration. This requires
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; some out-of-band way to prevent infinitely re-inlining and re-transforming the
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; code.
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;
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; RUN: opt < %s -passes='cgscc(inline,function(sroa,instcombine))' -inline-threshold=50 -S | FileCheck %s
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; The `test1_*` collection of functions form a directly cycling pattern.
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define void @test1_a(i8** %ptr) {
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; CHECK-LABEL: define void @test1_a(
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entry:
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call void @test1_b(i8* bitcast (void (i8*, i1, i32)* @test1_b to i8*), i1 false, i32 0)
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; Inlining and simplifying this call will reliably produce the exact same call,
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; over and over again. However, each inlining increments the count, and so we
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; expect this test case to stop after one round of inlining with a final
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; argument of '1'.
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; CHECK-NOT: call
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; CHECK: call void @test1_b(i8* bitcast (void (i8*, i1, i32)* @test1_b to i8*), i1 false, i32 1)
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; CHECK-NOT: call
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ret void
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}
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define void @test1_b(i8* %arg, i1 %flag, i32 %inline_count) {
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; CHECK-LABEL: define void @test1_b(
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entry:
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%a = alloca i8*
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store i8* %arg, i8** %a
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; This alloca and store should remain through any optimization.
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; CHECK: %[[A:.*]] = alloca
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; CHECK: store i8* %arg, i8** %[[A]]
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br i1 %flag, label %bb1, label %bb2
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bb1:
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call void @test1_a(i8** %a) noinline
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br label %bb2
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bb2:
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%cast = bitcast i8** %a to void (i8*, i1, i32)**
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%p = load void (i8*, i1, i32)*, void (i8*, i1, i32)** %cast
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%inline_count_inc = add i32 %inline_count, 1
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call void %p(i8* %arg, i1 %flag, i32 %inline_count_inc)
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; And we should continue to load and call indirectly through optimization.
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; CHECK: %[[CAST:.*]] = bitcast i8** %[[A]] to void (i8*, i1, i32)**
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; CHECK: %[[P:.*]] = load void (i8*, i1, i32)*, void (i8*, i1, i32)** %[[CAST]]
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; CHECK: call void %[[P]](
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ret void
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}
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define void @test2_a(i8** %ptr) {
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; CHECK-LABEL: define void @test2_a(
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entry:
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call void @test2_b(i8* bitcast (void (i8*, i8*, i1, i32)* @test2_b to i8*), i8* bitcast (void (i8*, i8*, i1, i32)* @test2_c to i8*), i1 false, i32 0)
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; Inlining and simplifying this call will reliably produce the exact same call,
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; but only after doing two rounds if inlining, first from @test2_b then
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; @test2_c. We check the exact number of inlining rounds before we cut off to
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; break the cycle by inspecting the last paramater that gets incremented with
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; each inlined function body.
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; CHECK-NOT: call
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; CHECK: call void @test2_b(i8* bitcast (void (i8*, i8*, i1, i32)* @test2_b to i8*), i8* bitcast (void (i8*, i8*, i1, i32)* @test2_c to i8*), i1 false, i32 2)
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; CHECK-NOT: call
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ret void
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}
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define void @test2_b(i8* %arg1, i8* %arg2, i1 %flag, i32 %inline_count) {
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; CHECK-LABEL: define void @test2_b(
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entry:
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%a = alloca i8*
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store i8* %arg2, i8** %a
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; This alloca and store should remain through any optimization.
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; CHECK: %[[A:.*]] = alloca
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; CHECK: store i8* %arg2, i8** %[[A]]
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br i1 %flag, label %bb1, label %bb2
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bb1:
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call void @test2_a(i8** %a) noinline
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br label %bb2
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bb2:
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%p = load i8*, i8** %a
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%cast = bitcast i8* %p to void (i8*, i8*, i1, i32)*
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%inline_count_inc = add i32 %inline_count, 1
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call void %cast(i8* %arg1, i8* %arg2, i1 %flag, i32 %inline_count_inc)
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; And we should continue to load and call indirectly through optimization.
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; CHECK: %[[CAST:.*]] = bitcast i8** %[[A]] to void (i8*, i8*, i1, i32)**
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; CHECK: %[[P:.*]] = load void (i8*, i8*, i1, i32)*, void (i8*, i8*, i1, i32)** %[[CAST]]
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; CHECK: call void %[[P]](
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ret void
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}
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define void @test2_c(i8* %arg1, i8* %arg2, i1 %flag, i32 %inline_count) {
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; CHECK-LABEL: define void @test2_c(
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entry:
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%a = alloca i8*
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store i8* %arg1, i8** %a
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; This alloca and store should remain through any optimization.
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; CHECK: %[[A:.*]] = alloca
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; CHECK: store i8* %arg1, i8** %[[A]]
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br i1 %flag, label %bb1, label %bb2
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bb1:
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call void @test2_a(i8** %a) noinline
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br label %bb2
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bb2:
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%p = load i8*, i8** %a
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%cast = bitcast i8* %p to void (i8*, i8*, i1, i32)*
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%inline_count_inc = add i32 %inline_count, 1
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call void %cast(i8* %arg1, i8* %arg2, i1 %flag, i32 %inline_count_inc)
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; And we should continue to load and call indirectly through optimization.
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; CHECK: %[[CAST:.*]] = bitcast i8** %[[A]] to void (i8*, i8*, i1, i32)**
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; CHECK: %[[P:.*]] = load void (i8*, i8*, i1, i32)*, void (i8*, i8*, i1, i32)** %[[CAST]]
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; CHECK: call void %[[P]](
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ret void
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}
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; Another infinite inlining case. The initial callgraph is like following:
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;
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; test3_a <---> test3_b
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; | ^
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; v |
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; test3_c <---> test3_d
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;
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; For all the call edges in the call graph, only test3_c and test3_d can be
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; inlined into test3_a, and no other call edge can be inlined.
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;
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; After test3_c is inlined into test3_a, the original call edge test3_a->test3_c
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; will be removed, a new call edge will be added and the call graph becomes:
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;
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; test3_a <---> test3_b
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; \ ^
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; v /
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; test3_c <---> test3_d
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; But test3_a, test3_b, test3_c and test3_d still belong to the same SCC.
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;
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; Then after test3_a->test3_d is inlined, when test3_a->test3_d is converted to
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; a ref edge, the original SCC will be split into two: {test3_c, test3_d} and
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; {test3_a, test3_b}, immediately after the newly added ref edge
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; test3_a->test3_c will be converted to a call edge, and the two SCCs will be
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; merged into the original one again. During this cycle, the original SCC will
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; be added into UR.CWorklist again and this creates an infinite loop.
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@a = global i64 0
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@b = global i64 0
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; Check test3_c is inlined into test3_a once and only once.
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; CHECK-LABEL: @test3_a(
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; CHECK: tail call void @test3_b()
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; CHECK-NEXT: tail call void @test3_d(i32 5)
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; CHECK-NEXT: %[[LD1:.*]] = load i64, i64* @a
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; CHECK-NEXT: %[[ADD1:.*]] = add nsw i64 %[[LD1]], 1
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; CHECK-NEXT: store i64 %[[ADD1]], i64* @a
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; CHECK-NEXT: %[[LD2:.*]] = load i64, i64* @b
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; CHECK-NEXT: %[[ADD2:.*]] = add nsw i64 %[[LD2]], 5
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; CHECK-NEXT: store i64 %[[ADD2]], i64* @b
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; CHECK-NEXT: ret void
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; Function Attrs: noinline
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define void @test3_a() #0 {
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entry:
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tail call void @test3_b()
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tail call void @test3_c(i32 5)
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%t0 = load i64, i64* @b
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%add = add nsw i64 %t0, 5
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store i64 %add, i64* @b
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ret void
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}
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; Function Attrs: noinline
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define void @test3_b() #0 {
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entry:
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tail call void @test3_a()
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%t0 = load i64, i64* @a
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%add = add nsw i64 %t0, 2
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store i64 %add, i64* @a
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ret void
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}
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define void @test3_d(i32 %i) {
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entry:
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%cmp = icmp eq i32 %i, 5
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br i1 %cmp, label %if.end, label %if.then
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if.then: ; preds = %entry
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%call = tail call i64 @random()
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%t0 = load i64, i64* @a
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%add = add nsw i64 %t0, %call
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store i64 %add, i64* @a
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br label %if.end
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if.end: ; preds = %entry, %if.then
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tail call void @test3_c(i32 %i)
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tail call void @test3_b()
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%t6 = load i64, i64* @a
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%add79 = add nsw i64 %t6, 3
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store i64 %add79, i64* @a
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ret void
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}
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define void @test3_c(i32 %i) {
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entry:
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%cmp = icmp eq i32 %i, 5
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br i1 %cmp, label %if.end, label %if.then
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if.then: ; preds = %entry
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%call = tail call i64 @random()
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%t0 = load i64, i64* @a
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%add = add nsw i64 %t0, %call
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store i64 %add, i64* @a
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br label %if.end
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if.end: ; preds = %entry, %if.then
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tail call void @test3_d(i32 %i)
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%t6 = load i64, i64* @a
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%add85 = add nsw i64 %t6, 1
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store i64 %add85, i64* @a
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ret void
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}
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declare i64 @random()
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attributes #0 = { noinline }
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