ee5585ed09
Improve and enable folding of conditional branches with tail calls. 1. Make it so that conditional tail calls can be emitted even when there are multiple predecessors. 2. Don't guard the transformation behind -Os. The rationale for guarding it was static-prediction can be affected by whether the branch is forward of backward. This is no longer true for almost any X86 cpus (anything newer than `SnB`) so is no longer a meaningful concern. Reviewed By: pengfei Differential Revision: https://reviews.llvm.org/D140931
65 lines
1.3 KiB
LLVM
65 lines
1.3 KiB
LLVM
; RUN: llc < %s -mtriple=i686-apple-darwin | FileCheck %s --check-prefix=DARWIN
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; RUN: llc < %s -mtriple=i686-windows-msvc | FileCheck %s --check-prefix=WIN32
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; RUN: llc < %s -mtriple=x86_64-windows-msvc | FileCheck %s --check-prefix=WIN64
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declare extern_weak void @foo(...)
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define void @bar() {
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entry:
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br i1 icmp ne (ptr @foo, ptr null), label %if.then, label %if.end
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if.then:
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tail call void (...) @foo( )
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ret void
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if.end:
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ret void
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}
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; DARWIN-LABEL: _bar:
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; DARWIN: cmpl $0, L_foo$non_lazy_ptr
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; DARWIN: jne _foo ## TAILCALL
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; WIN32-LABEL: _bar:
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; WIN32: cmpl $0, .refptr._foo
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; WIN32: jmpl *.refptr._foo
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; WIN64-LABEL: bar:
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; WIN64: cmpq $0, .refptr.foo(%rip)
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; WIN64: jmpq *.refptr.foo
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declare extern_weak i32 @X(ptr)
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@Y = global ptr @X ; <ptr> [#uses=0]
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; DARWIN-LABEL: _Y:
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; DARWIN: .long _X
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; WIN32-LABEL: _Y:
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; WIN32: .long _X
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; WIN64-LABEL: Y:
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; WIN64: .quad X
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; DARWIN: .weak_reference _foo
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; DARWIN: .weak_reference _X
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; WIN32: .section .rdata$.refptr._foo,"dr",discard,.refptr._foo
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; WIN32: .globl .refptr._foo
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; WIN32: .refptr._foo:
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; WIN32: .long _foo
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; WIN32: .weak _foo
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; WIN32: .weak _X
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; WIN64: .section .rdata$.refptr.foo,"dr",discard,.refptr.foo
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; WIN64: .globl .refptr.foo
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; WIN64: .refptr.foo:
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; WIN64: .quad foo
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; WIN64: .weak foo
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; WIN64: .weak X
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