I agree what you said about different code generated with clang and GCC
generates. In this case, we should throw an error (err_late_asm_label).
But in this example, there is no use of the function. They are just
redundant declarations and there is no actual code generated.
So I suggest we just give warnings for this case. Otherwise, it will
break existing code like some SPEC benchmarks.
Please review my 2nd patch.
Weiming
On 1/14/2016 2:28 PM, Nick Lewycky wrote:
On 14 January 2016 at 10:38, Weiming Zhao via cfe-commits
<cfe-commits@lists.llvm.org <mailto:cfe-commits@lists.llvm.org>> wrote:
weimingz added a comment.
Hi Nick,
Below is a reduced code:
t.c:
static long double acoshl (long double __x) __asm__ ("" "acosh")
; // this is from
<gcc4.9>/arm-linux-gnueabi/libc/usr/include/bits/mathcalls.h
extern long double acoshl (long double) __asm__ (""
"__acoshl_finite") ; // this is from existing code
GCC gives warning like:
/tmp/t.c:2:1: warning: asm declaration ignored due to conflict
with previous rename [-Wpragmas]
extern long double acoshl (long double) __asm__ (""
"__acoshl_finite") ;
That's the same case as in this testcase:
void foo() __asm__("one");
void foo() __asm__("two");
void test() { foo(); }
GCC emits a call to 'one' while Clang emits a call to 'two'. This is a
real bug. Please don't downgrade this to a warning.
As an alternative, I would accept a patch which changes how clang
generates code so that it also produces a call to 'one', with a
warning. It looks like what we need to do is drop subsequent asm label
declarations on functions that already have one.
Nick
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