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https://github.com/c64scene-ar/llvm-6502.git
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072ebe59e2
clang optimizes tail calls, as in this example:
int foo(void);
int bar(void) {
return foo();
}
where the call is transformed to:
calll .L0$pb
.L0$pb:
popl %eax
.Ltmp0:
addl $_GLOBAL_OFFSET_TABLE_+(.Ltmp0-.L0$pb), %eax
movl foo@GOT(%eax), %eax
popl %ebp
jmpl *%eax # TAILCALL
However, the GOT references must all be resolved at dlopen() time, and so this
approach cannot be used with lazy dynamic linking (e.g. using RTLD_LAZY), which
usually populates the PLT with stubs that perform the actual resolving.
This patch changes X86TargetLowering::LowerCall() to skip tail call
optimization, if the called function is a global or external symbol.
Patch by Dimitry Andric!
PR15086
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195318 91177308-0d34-0410-b5e6-96231b3b80d8
23 lines
682 B
LLVM
23 lines
682 B
LLVM
; RUN: llc < %s -relocation-model=pic -mattr=+sse2 | FileCheck %s
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target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32"
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target triple = "i386-unknown-freebsd9.0"
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define double @test1(double %x) nounwind readnone {
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; CHECK-LABEL: test1:
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; CHECK: calll foo@PLT
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%1 = tail call double @foo(double %x) nounwind readnone
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ret double %1
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}
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declare double @foo(double) readnone
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define double @test2(double %x) nounwind readnone {
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; CHECK-LABEL: test2:
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; CHECK: calll sin@PLT
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%1 = tail call double @sin(double %x) nounwind readnone
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ret double %1
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}
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declare double @sin(double) readnone
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