http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59379
--- Comment #19 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to Uroš Bizjak from comment #18)
> I have checked that this patch with the testcase from Comment #9, using "-O
> -march=corei7 -mtune=slm" compile options. The resulting binary worked OK.
Yes, the resulting GCC works correctly. However, we generate
extra
(set (reg:DI) (zero_extend:DI (reg:SI)))
It is because we generate
(set (reg:SI) (reg:SI)
(set (reg:DI) (zero_extend:DI (reg:SI)))
REE pass doesn't know
(set (reg:SI) (reg:SI)
has an implicit ZERO_EXTEND. Here is a testcase:
---foo.c---
extern __thread unsigned int __bid_IDEC_glbflags;
typedef unsigned long long UINT64;
typedef __attribute__ ((aligned(16))) struct
{
UINT64 w[2];
} UINT128;
extern UINT64 __bid64_from_uint64 (UINT64);
extern void __bid_round64_2_18 (int q,
int x,
UINT64 C,
UINT64 * ptr_Cstar,
int *delta_exp,
int *ptr_is_midpoint_lt_even,
int *ptr_is_midpoint_gt_even,
int *ptr_is_inexact_lt_midpoint,
int *ptr_is_inexact_gt_midpoint);
extern void __bid_round128_19_38 (int q,
int x,
UINT128 C,
UINT128 * ptr_Cstar,
int *delta_exp,
int *ptr_is_midpoint_lt_even,
int *ptr_is_midpoint_gt_even,
int *ptr_is_inexact_lt_midpoint,
int *ptr_is_inexact_gt_midpoint);
UINT64
__bid64_from_uint64 (UINT64 x)
{
UINT64 res;
UINT128 x128, res128;
unsigned int q, ind;
int incr_exp = 0;
int is_midpoint_lt_even = 0, is_midpoint_gt_even = 0;
int is_inexact_lt_midpoint = 0, is_inexact_gt_midpoint = 0;
if (x <= 0x002386F26FC0ffffull) {
if (x < 0x0020000000000000ull) {
res = 0x31c0000000000000ull | x;
} else {
res = 0x6c70000000000000ull | (x & 0x0007ffffffffffffull);
}
}
else
{
if (x < 0x16345785d8a0000ull) {
q = 17;
ind = 1;
} else if (x < 0xde0b6b3a7640000ull) {
q = 18;
ind = 2;
} else if (x < 0x8ac7230489e80000ull) {
q = 19;
ind = 3;
} else {
q = 20;
ind = 4;
}
if (q <= 19) {
__bid_round64_2_18 (
q, ind, x, &res, &incr_exp,
&is_midpoint_lt_even, &is_midpoint_gt_even,
&is_inexact_lt_midpoint, &is_inexact_gt_midpoint);
}
else {
x128.w[1] = 0x0;
x128.w[0] = x;
__bid_round128_19_38 (q, ind, x128, &res128, &incr_exp,
&is_midpoint_lt_even, &is_midpoint_gt_even,
&is_inexact_lt_midpoint, &is_inexact_gt_midpoint);
res = res128.w[0];
}
if (incr_exp)
ind++;
if (is_inexact_lt_midpoint || is_inexact_gt_midpoint ||
is_midpoint_lt_even || is_midpoint_gt_even)
*&__bid_IDEC_glbflags |= 0x00000020;
if (res < 0x0020000000000000ull) {
res = (((UINT64) ind + 398) << 53) | res;
} else
{
res = 0x6000000000000000ull | (((UINT64) ind + 398) << 51) |
(res & 0x0007ffffffffffffull);
}
}
return(res);;
}
-----------
Compiling with -fPIC -O2, the differences between your patch and mine
are
--- bad.s 2014-01-19 06:10:28.006570325 -0800
+++ foo.s 2014-01-19 06:11:46.117754696 -0800
@@ -84,19 +84,18 @@ __bid64_from_uint64:
movabsq $9007199254740991, %rax
cmpq %rax, %rbx
jbe .L23
- movl %ebp, %edx
leaq 88(%rsp), %rsp
.cfi_remember_state
.cfi_def_cfa_offset 24
movabsq $2251799813685247, %rax
- movl %edx, %edx
+ movl %ebp, %edx
andq %rbx, %rax
- movabsq $6917529027641081856, %rcx
popq %rbx
.cfi_def_cfa_offset 16
+ movabsq $6917529027641081856, %rcx
addq $398, %rdx
- orq %rcx, %rax
salq $51, %rdx
+ orq %rcx, %rax
popq %rbp
.cfi_def_cfa_offset 8
orq %rdx, %rax
@@ -154,7 +153,6 @@ __bid64_from_uint64:
leaq 88(%rsp), %rsp
.cfi_remember_state
.cfi_def_cfa_offset 24
- movl %eax, %eax
addq $398, %rax
salq $53, %rax
orq %rbx, %rax
My patch removes 2 extra
(set (reg:DI) (zero_extend:DI (reg:SI)))
