Merging r195318:

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r195318 | void | 2013-11-20 23:04:30 -0800 (Wed, 20 Nov 2013) | 29 lines

The basic problem is that some mainstream programs cannot deal with the way
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
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_34@195319 91177308-0d34-0410-b5e6-96231b3b80d8

0 files changed, 0 insertions, 0 deletions