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fc4e6d1d1a
Summary:
It was supposed that Ref LazyCallGraph::Edge's were being inserted by
inlining, but that doesn't seem to be the case. Instead, it seems that
there was no test for a blockaddress Constant in an instruction that
referenced the function that contained the instruction. Ex:
```
define void @f() {
%1 = alloca i8*, align 8
2:
store i8* blockaddress(@f, %2), i8** %1, align 8
ret void
}
```
When iterating blockaddresses, do not add the function they refer to
back to the worklist if the blockaddress is referring to the contained
function (as opposed to an external function).
Because blockaddress has sligtly different semantics than GNU C's
address of labels, there are 3 cases that can occur with blockaddress,
where only 1 can happen in GNU C due to C's scoping rules:
* blockaddress is within the function it refers to (possible in GNU C).
* blockaddress is within a different function than the one it refers to
(not possible in GNU C).
* blockaddress is used in to declare a global (not possible in GNU C).
The second case is tested in:
```
$ ./llvm/build/unittests/Analysis/AnalysisTests \
--gtest_filter=LazyCallGraphTest.HandleBlockAddress
```
This patch adjusts the iteration of blockaddresses in
LazyCallGraph::visitReferences to not revisit the blockaddresses
function in the first case.
The Linux kernel contains code that's not semantically valid at -O0;
specifically code passed to asm goto. It requires that asm goto be
inline-able. This patch conservatively does not attempt to handle the
more general case of inlining blockaddresses that have non-callbr users
(pr/39560).
https://bugs.llvm.org/show_bug.cgi?id=39560
https://bugs.llvm.org/show_bug.cgi?id=40722
https://github.com/ClangBuiltLinux/linux/issues/6
https://reviews.llvm.org/rL212077
Reviewers: jyknight, eli.friedman, chandlerc
Reviewed By: chandlerc
Subscribers: george.burgess.iv, nathanchance, mgorny, craig.topper, mengxu.gatech, void, mehdi_amini, E5ten, chandlerc, efriedma, eraman, hiraditya, haicheng, pirama, llvm-commits, srhines
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D58260
llvm-svn: 361173
55 lines
1.7 KiB
LLVM
55 lines
1.7 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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define dso_local i32 @main() #0 {
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%1 = alloca i32, align 4
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store i32 0, i32* %1, align 4
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%2 = call i32 @t32(i32 0)
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ret i32 %2
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}
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define internal i32 @t32(i32) #0 {
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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,X,X,~{dirflag},~{fpsr},~{flags}"(i32 %4, i8* blockaddress(@t32, %7), i8* blockaddress(@t32, %6)) #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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; Check that @t32 no longer exists after inlining, as it has now been inlined
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; into @main.
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; CHECK-NOT: @t32
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; CHECK: define dso_local i32 @main
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; CHECK: callbr void asm sideeffect "testl $0, $0; jne ${1:l};", "r,X,X,~{dirflag},~{fpsr},~{flags}"(i32 %6, i8* blockaddress(@main, %9), i8* blockaddress(@main, %8))
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; CHECK: to label %7 [label %9, label %8]
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; CHECK: 7:
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; CHECK-NEXT: store i32 0, i32* %1, align 4
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; CHECK-NEXT: br label %t32.exit
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; CHECK: 8:
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; CHECK-NEXT: store i32 1, i32* %1, align 4
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; CHECK-NEXT: br label %t32.exit
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; CHECK: 9:
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; CHECK-NEXT: store i32 2, i32* %1, align 4
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; CHECK-NEXT: br label %t32.exit
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; CHECK: t32.exit:
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; CHECK-NEXT: %10 = load i32, i32* %1, align 4
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; CHECK: ret i32 %10
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