https://llvm.org/bugs/show_bug.cgi?id=28633
Bug ID: 28633
Summary: clang aarch64 compiler crash on inline constraints
Product: new-bugs
Version: 3.8
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: new bugs
Assignee: unassignedb...@nondot.org
Reporter: fbarch...@google.com
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
This inline aarch64 function causes a segfault in clang
// This function known to cause compiler fault on clang 64 bit.
int saturate_32bit_to_16bit(int a) {
int ret;
asm volatile ("sqxtn h0, %s[a]\n"
"sxtl v0.4s, v0.4h\n"
"fmov %w[ret], s0\n"
: [ret] "=&r" (ret)
: [a] "w" (a)
: "v0" );
return ret;
}
Expected Results:
same as gcc - generate valid code.
Actual Results:
./clang saturate_test.c -O2 -target aarch64-none-linux-android -c
.../saturate_test.c:5:19: error: couldn't allocate input reg for constraint 'w'
asm volatile ("sqxtn h0, %s[a]\n"
^
clang-3.8: error: unable to execute command: Segmentation fault (core dumped)
clang-3.8: error: clang frontend command failed due to signal (use -v to see
invocation)
clang version 3.8.1
Target: aarch64-none-linux-android
Thread model: posix
This also fails:
static inline int saturate_32bit_to_16bit(int a) {
int ret;
asm volatile ("sqxtn %h[ret], %s[a]\n"
"sxtl %[ret].4s, %[ret].4h\n"
: [ret] "=w" (ret)
: [a] "w" (a)
:);
return ret;
}
This works
static inline int saturate_32bit_to_16bit(int a) {
int ret;
asm volatile ("fmov s0, %w[a]\n"
"sqxtn h0, s0\n"
"sxtl v0.4s, v0.4h\n"
"fmov %w[ret], s0\n"
: [ret] "=&r" (ret)
: [a] "r" (a)
: "v0" );
return ret;
}
This similar function works
static inline int saturate_float_to_16bit(float a) {
int ret;
asm volatile ("fcvtas %s[ret], %s[a]\n"
"sqxtn %h[ret], %s[ret]\n"
"sxtl %[ret].4s, %[ret].4h\n"
: [ret] "=w" (ret)
: [a] "w" (a)
:);
return ret;
}
Additional Information:
all variations work ok in gcc 4.9
Tested/fails on OSX and Linux.
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