2a721374ae
Following some recent discussions, this changes the representation
of callbrs in IR. The current blockaddress arguments are replaced
with `!` label constraints that refer directly to callbr indirect
destinations:
; Before:
%res = callbr i8* asm "", "=r,r,i"(i8* %x, i8* blockaddress(@test8, %foo))
to label %asm.fallthrough [label %foo]
; After:
%res = callbr i8* asm "", "=r,r,!i"(i8* %x)
to label %asm.fallthrough [label %foo]
The benefit of this is that we can easily update the successors of
a callbr, without having to worry about also updating blockaddress
references. This should allow us to remove some limitations:
* Allow unrolling/peeling/rotation of callbr, or any other
clone-based optimizations
(https://github.com/llvm/llvm-project/issues/41834)
* Allow duplicate successors
(https://github.com/llvm/llvm-project/issues/45248)
This is just the IR representation change though, I will follow up
with patches to remove limtations in various transformation passes
that are no longer needed.
Differential Revision: https://reviews.llvm.org/D129288
131 lines
3.5 KiB
LLVM
131 lines
3.5 KiB
LLVM
; RUN: opt -inline -S < %s | FileCheck %s
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; RUN: opt -passes='cgscc(inline)' -S < %s | FileCheck %s
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; PR10162
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; Make sure doit is not inlined since the blockaddress is taken
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; which could be unsafe
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; CHECK: store i8* blockaddress(@doit, %here), i8** %pptr, align 8
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@i = global i32 1, align 4
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@ptr1 = common global i8* null, align 8
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define void @doit(i8** nocapture %pptr, i32 %cond) nounwind uwtable {
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entry:
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%tobool = icmp eq i32 %cond, 0
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br i1 %tobool, label %if.end, label %here
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here:
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store i8* blockaddress(@doit, %here), i8** %pptr, align 8
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br label %if.end
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if.end:
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ret void
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}
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define void @f(i32 %cond) nounwind uwtable {
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entry:
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call void @doit(i8** @ptr1, i32 %cond)
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ret void
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}
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; PR27233: We can inline @run into @init. Don't crash on it.
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;
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; CHECK-LABEL: define void @init
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; CHECK: store i8* blockaddress(@run, %bb)
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; CHECK-SAME: @run.bb
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define void @init() {
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entry:
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call void @run()
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ret void
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}
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define void @run() {
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entry:
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store i8* blockaddress(@run, %bb), i8** getelementptr inbounds ([1 x i8*], [1 x i8*]* @run.bb, i64 0, i64 0), align 8
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ret void
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bb:
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unreachable
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}
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@run.bb = global [1 x i8*] zeroinitializer
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; Check that a function referenced by a global blockaddress wont be inlined,
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; even if it contains a callbr. We might be able to relax this in the future
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; as long as the global blockaddress is updated correctly.
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@ba = internal global i8* blockaddress(@foo, %7), align 8
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define internal i32 @foo(i32) {
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%2 = alloca i32, align 4
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%3 = alloca i32, align 4
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store i32 %0, i32* %3, align 4
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%4 = load i32, i32* %3, align 4
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callbr void asm sideeffect "testl $0, $0; jne ${1:l};", "r,!i,!i,~{dirflag},~{fpsr},~{flags}"(i32 %4) #1
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to label %5 [label %7, label %6]
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; <label>:5: ; preds = %1
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store i32 0, i32* %2, align 4
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br label %8
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; <label>:6: ; preds = %1
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store i32 1, i32* %2, align 4
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br label %8
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; <label>:7: ; preds = %1
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store i32 2, i32* %2, align 4
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br label %8
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; <label>:8: ; preds = %7, %6, %5
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%9 = load i32, i32* %2, align 4
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ret i32 %9
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}
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define dso_local i32 @bar() {
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%1 = call i32 @foo(i32 0)
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ret i32 %1
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}
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; CHECK: define dso_local i32 @bar() {
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; CHECK: %1 = call i32 @foo(i32 0)
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; CHECK: ret i32 %1
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; CHECK: }
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; Triple check that even with a global aggregate whose member is a blockaddress,
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; we still don't inline referred to functions.
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%struct.foo = type { i8* }
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@my_foo = dso_local global %struct.foo { i8* blockaddress(@baz, %7) }
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define internal i32 @baz(i32) {
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%2 = alloca i32, align 4
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%3 = alloca i32, align 4
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store i32 %0, i32* %3, align 4
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%4 = load i32, i32* %3, align 4
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callbr void asm sideeffect "testl $0, $0; jne ${1:l};", "r,!i,!i,~{dirflag},~{fpsr},~{flags}"(i32 %4) #1
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to label %5 [label %7, label %6]
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; <label>:5: ; preds = %1
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store i32 0, i32* %2, align 4
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br label %8
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; <label>:6: ; preds = %1
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store i32 1, i32* %2, align 4
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br label %8
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; <label>:7: ; preds = %1
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store i32 2, i32* %2, align 4
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br label %8
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; <label>:8: ; preds = %7, %6, %5
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%9 = load i32, i32* %2, align 4
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ret i32 %9
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}
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define dso_local i32 @quux() {
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%1 = call i32 @baz(i32 0)
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ret i32 %1
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}
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; CHECK: define dso_local i32 @quux() {
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; CHECK: %1 = call i32 @baz(i32 0)
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; CHECK: ret i32 %1
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; CHECK: }
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