| Summary: | [7 Regression] Illegal instruction in generated code | ||
|---|---|---|---|
| Product: | gcc | Reporter: | Dmitry Babokin <babokin> |
| Component: | tree-optimization | Assignee: | Jakub Jelinek <jakub> |
| Status: | RESOLVED FIXED | ||
| Severity: | normal | CC: | bonzini, jakub |
| Priority: | P1 | Keywords: | wrong-code |
| Version: | 7.0 | ||
| Target Milestone: | 7.0 | ||
| Host: | Target: | ||
| Build: | Known to work: | ||
| Known to fail: | Last reconfirmed: | 2016-12-07 00:00:00 | |
| Bug Depends on: | |||
| Bug Blocks: | 103035 | ||
| Attachments: |
reproducer
gcc7-pr78720.patch |
||
|
Description
Dmitry Babokin
2016-12-07 19:35:01 UTC
g++ -O2 -S illegal_inst.cpp -o - | c++filt
foo():
.LFB12:
.cfi_startproc
ud2
.cfi_endproc
% cat illegal_inst.cpp
extern signed char var_13;
long int rrr;
void foo() {
rrr = !0 % ((var_13 < 0) << 21);
}
Started with r243255: commit 458de25d72182951e17489052becf952f6b63592 Author: bonzini <bonzini@138bc75d-0d04-0410-961f-82ee72b054a4> Date: Mon Dec 5 13:19:34 2016 +0000 gcc: * match.pd: Simplify X ? C : 0 where C is a power of 2 and X tests a single bit. From:
void foo() ()
{
signed char var_13.0_1;
signed char _2;
int _3;
int _4;
int _5;
long int _6;
<bb 2> [0.0%]:
var_13.0_1 = var_13;
_2 = var_13.0_1 >> -14;
_3 = (int) _2;
_4 = _3 & 2097152;
_5 = 1 % _4;
_6 = (long int) _5;
rrr = _6;
return;
}
To (ccp1):
void foo() ()
{
signed char var_13.0_1;
int _5;
long int _6;
<bb 2> [0.0%]:
var_13.0_1 = var_13;
_5 = 1 % 0;
_6 = (long int) _5;
rrr = _6;
return;
}
Already the >> -14 looks wrong. Created attachment 40284 [details] gcc7-pr78720.patch Untested fix. Author: jakub Date: Sat Dec 10 12:06:12 2016 New Revision: 243516 URL: https://gcc.gnu.org/viewcvs?rev=243516&root=gcc&view=rev Log: PR tree-optimization/78720 * match.pd (A < 0 ? C : 0): Only optimize for signed A. If shift is negative, sign extend to @1's type and than AND with C. * gcc.c-torture/execute/pr78720.c: New test. Added: trunk/gcc/testsuite/gcc.c-torture/execute/pr78720.c Modified: trunk/gcc/ChangeLog trunk/gcc/match.pd trunk/gcc/testsuite/ChangeLog Fixed. |