https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85726
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
Priority|P3 |P2
Target Milestone|--- |6.5
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed. On x86 the diff from GCC 4.8 to GCC 7 at -O2 is
@@ -6,8 +6,16 @@
x:
.LFB0:
.cfi_startproc
+ movl %edi, %eax
+ movl $715827883, %edx
+ imull %edx
+ movl %edi, %eax
+ sarl $31, %eax
+ sarl $3, %edx
+ subl %eax, %edx
leal 15(%rdi), %eax
testl %edi, %edi
+ movl %edx, ww(%rip)
movl $1431655766, %edx
cmovs %eax, %edi
movl %edi, %ecx
@@ -15,9 +23,9 @@
sarl $4, %ecx
movl %ecx, %eax
imull %edx
- subl %edi, %edx
- leal (%rdx,%rdx,2), %eax
- movl %edx, ww(%rip)
+ movl %edx, %eax
+ subl %edi, %eax
+ leal (%rax,%rax,2), %eax
subl %eax, %ecx
movl %ecx, %eax
ret
