| Message ID | VI1PR0802MB21769664EDAAFBDDDE5C87BFE7290@VI1PR0802MB2176.eurprd08.prod.outlook.com |
|---|---|
| State | New |
| Headers | show |
On Wed, Mar 1, 2017 at 1:03 PM, Bin Cheng <Bin.Cheng@arm.com> wrote: > Hi, > As reported in PR66768, IVOPTs drops address-space information. Root cause is IVOPTs fails to preserve base-object during identifying/rewriting address type iv_use for pointers converted from constant values. This patch just skips address type iv_use if base-object can't be determined. In the future, better handling of base-object is needed to fix the issue. Benchmark data show the added condition is only triggered twice in spec2k6, and the two cases are actually null-pointer references. I believe that code is dead in benchmark and is never executed. > > Bootstrap and test on x86_64. Is it OK? Ok. Richard. > 2017-02-27 Bin Cheng <bin.cheng@arm.com> > > PR tree-optimization/66768 > * tree-ssa-loop-ivopts.c (find_interesting_uses_address): Skip addr > iv_use if base object can't be determined. > > 2017-02-27 Bin Cheng <bin.cheng@arm.com> > > PR tree-optimization/66768 > * gcc.target/i386/pr66768.c: New test.
diff --git a/gcc/testsuite/gcc.target/i386/pr66768.c b/gcc/testsuite/gcc.target/i386/pr66768.c new file mode 100644 index 0000000..9a8ad1f --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr66768.c @@ -0,0 +1,17 @@ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ + +typedef __seg_gs struct foo_s { + int a[20]; +} foo_t; + +int sum(void) +{ + const foo_t *p = (const foo_t *)0x1234; + int i, total=0; + for (i=0; i<20; i++) + total += p->a[i]; + return total; +} + +/* { dg-final { scan-assembler "add*.\[ \t\]%gs:" } } */ diff --git a/gcc/tree-ssa-loop-ivopts.c b/gcc/tree-ssa-loop-ivopts.c index c9d16b2..f3ad373 100644 --- a/gcc/tree-ssa-loop-ivopts.c +++ b/gcc/tree-ssa-loop-ivopts.c @@ -2324,6 +2324,10 @@ find_interesting_uses_address (struct ivopts_data *data, gimple *stmt, } civ = alloc_iv (data, base, step); + /* Fail if base object of this memory reference is unknown. */ + if (civ->base_object == NULL_TREE) + goto fail; + record_group_use (data, op_p, civ, stmt, USE_ADDRESS); return;