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* [Bug c/67242] New: Missing optimization with float
@ 2015-08-16 20:12 f.boesing at gmx dot de
2015-08-16 20:14 ` [Bug c/67242] " f.boesing at gmx dot de
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: f.boesing at gmx dot de @ 2015-08-16 20:12 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67242
Bug ID: 67242
Summary: Missing optimization with float
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: f.boesing at gmx dot de
Target Milestone: ---
testcase:
int n, dummy;
float dummyfloat;
void bug(void)
{
for(n=0; n<1000; n++)
dummy = n;
for(n=0; n<1000; n++)
dummyfloat = n;
}
the first loop (dummy=) is optimized away with -O2 and -O3
the second (dummyfloat=) NOT.
Tested with 4.9.2 & 4.9.3, targets x86-64, arm-thumb and arm.
commandline: gcc -O2 bug.c -S
^ permalink raw reply [flat|nested] 5+ messages in thread* [Bug c/67242] Missing optimization with float 2015-08-16 20:12 [Bug c/67242] New: Missing optimization with float f.boesing at gmx dot de @ 2015-08-16 20:14 ` f.boesing at gmx dot de 2015-08-16 20:28 ` f.boesing at gmx dot de ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: f.boesing at gmx dot de @ 2015-08-16 20:14 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67242 --- Comment #1 from Frank <f.boesing at gmx dot de> --- works ok with local variables. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c/67242] Missing optimization with float 2015-08-16 20:12 [Bug c/67242] New: Missing optimization with float f.boesing at gmx dot de 2015-08-16 20:14 ` [Bug c/67242] " f.boesing at gmx dot de @ 2015-08-16 20:28 ` f.boesing at gmx dot de 2015-08-17 7:24 ` [Bug tree-optimization/67242] Missing optimization with float IV in SCEV-CCP rguenth at gcc dot gnu.org 2021-12-15 21:56 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: f.boesing at gmx dot de @ 2015-08-16 20:28 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67242 --- Comment #2 from Frank <f.boesing at gmx dot de> --- x86-64: .file "bug.c" .section .text.unlikely,"x" .LCOLDB0: .text .LHOTB0: .p2align 4,,15 .globl bug .def bug; .scl 2; .type 32; .endef .seh_proc bug bug: .seh_endprologue movl $999, dummy(%rip) xorl %eax, %eax .p2align 4,,10 .L2: pxor %xmm0, %xmm0 cvtsi2ss %eax, %xmm0 addl $1, %eax cmpl $1000, %eax jne .L2 movss %xmm0, dummyfloat(%rip) movl $1000, n(%rip) ret .seh_endproc .section .text.unlikely,"x" .LCOLDE0: .text .LHOTE0: .comm dummyfloat, 4, 2 .comm dummy, 4, 2 .comm n, 4, 2 .ident "GCC: (tdm64-1) 4.9.2" arm-thumb, soft float: .cpu arm7tdmi .fpu softvfp .eabi_attribute 20, 1 .eabi_attribute 21, 1 .eabi_attribute 23, 3 .eabi_attribute 24, 1 .eabi_attribute 25, 1 .eabi_attribute 26, 1 .eabi_attribute 30, 2 .eabi_attribute 34, 0 .eabi_attribute 18, 4 .code 16 .file "bug.c" .global __aeabi_i2f .text .align 2 .global bug .code 16 .thumb_func .type bug, %function bug: push {r3, r4, r5, lr} mov r5, #250 mov r4, #0 ldr r2, .L5 ldr r3, .L5+4 str r2, [r3] lsl r5, r5, #2 .L2: mov r0, r4 add r4, r4, #1 bl __aeabi_i2f cmp r4, r5 bne .L2 ldr r3, .L5+8 str r0, [r3] ldr r3, .L5+12 @ sp needed str r4, [r3] pop {r3, r4, r5} pop {r0} bx r0 .L6: .align 2 .L5: .word 999 .word dummy .word dummyfloat .word n .size bug, .-bug .comm dummyfloat,4,4 .comm dummy,4,4 .comm n,4,4 .ident "GCC: (GNU Tools for ARM Embedded Processors) 4.9.3 20150529 (release) [ARM/embedded-4_9-branch revision 224288]" ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/67242] Missing optimization with float IV in SCEV-CCP 2015-08-16 20:12 [Bug c/67242] New: Missing optimization with float f.boesing at gmx dot de 2015-08-16 20:14 ` [Bug c/67242] " f.boesing at gmx dot de 2015-08-16 20:28 ` f.boesing at gmx dot de @ 2015-08-17 7:24 ` rguenth at gcc dot gnu.org 2021-12-15 21:56 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: rguenth at gcc dot gnu.org @ 2015-08-17 7:24 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67242 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |missed-optimization Status|UNCONFIRMED |NEW Last reconfirmed| |2015-08-17 Summary|Missing optimization with |Missing optimization with |float |float IV in SCEV-CCP Ever confirmed|0 |1 Known to fail| |5.2.0 --- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> --- Confirmed. This is SCEV-const-prop not handling floats (obviously). The trick could be to handle this kind of DEFs of loop-closed PHI uses specially (use the evolution of the source). ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/67242] Missing optimization with float IV in SCEV-CCP 2015-08-16 20:12 [Bug c/67242] New: Missing optimization with float f.boesing at gmx dot de ` (2 preceding siblings ...) 2015-08-17 7:24 ` [Bug tree-optimization/67242] Missing optimization with float IV in SCEV-CCP rguenth at gcc dot gnu.org @ 2021-12-15 21:56 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu.org @ 2021-12-15 21:56 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67242 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Severity|normal |enhancement ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-12-15 21:56 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2015-08-16 20:12 [Bug c/67242] New: Missing optimization with float f.boesing at gmx dot de 2015-08-16 20:14 ` [Bug c/67242] " f.boesing at gmx dot de 2015-08-16 20:28 ` f.boesing at gmx dot de 2015-08-17 7:24 ` [Bug tree-optimization/67242] Missing optimization with float IV in SCEV-CCP rguenth at gcc dot gnu.org 2021-12-15 21:56 ` pinskia at gcc dot gnu.org
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