| Message ID | 20171230194206.GQ1833@tucnak |
|---|---|
| State | New |
| Headers | show |
| Series | Fix ICE with LOOP_VECTORIZED ifn (PR tree-optimization/83581) | expand |
On December 30, 2017 8:42:06 PM GMT+01:00, Jakub Jelinek <jakub@redhat.com> wrote: >Hi! > >The problem on this testcase is that ldist pass changes some >GIMPLE_CONDs >into 0 != 0 or similar, but the pass doesn't perform any cleanups, then >ifcvt is run and does completely useless work of duplicating dead loops >and guarding them with LOOP_VECTORIZED ifns, and then during the ifcvt >cfg cleanup the dead loops are optimized away, but nothing removes the >corresponding LOOP_VECTORIZED ifns. While perhaps we'll need to hook >into >the loop removal and remove the dead ifns or remove the dead ifns >during >vectorizer pass using a more expensive way at some point (e.g. by >scanning >all bb's last insn for GIMPLE_COND checking LOOP_VECTORIZED) at some >point, >in this case it seems to me clearly preferrable to let the ldist pass >clean >up after itself, so that we don't do useless work in ifcvt from the >beginning. > >Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? OK. Richard. >2017-12-30 Jakub Jelinek <jakub@redhat.com> > > PR tree-optimization/83581 > * tree-loop-distribution.c (pass_loop_distribution::execute): Return > TODO_cleanup_cfg if any changes have been made. > > * gcc.dg/pr83581.c: New test. > >--- gcc/tree-loop-distribution.c.jj 2017-12-21 09:43:17.486071696 +0100 >+++ gcc/tree-loop-distribution.c 2017-12-30 16:54:08.106143319 +0100 >@@ -3103,7 +3103,7 @@ pass_loop_distribution::execute (functio > > checking_verify_loop_structure (); > >- return 0; >+ return changed ? TODO_cleanup_cfg : 0; > } > > } // anon namespace >--- gcc/testsuite/gcc.dg/pr83581.c.jj 2017-12-30 16:55:35.950164947 >+0100 >+++ gcc/testsuite/gcc.dg/pr83581.c 2017-12-30 16:55:17.520160406 +0100 >@@ -0,0 +1,21 @@ >+/* PR tree-optimization/83581 */ >+/* { dg-do compile } */ >+/* { dg-options "-O3 -fno-tree-copy-prop -fno-tree-loop-im" } */ >+ >+int a, b, c; >+ >+int >+foo (int x) >+{ >+ int *d = &x; >+ while (a < 1) >+ { >+ for (b = 0; b < 2; ++b) >+ { >+ *d += !!x + 1; >+ d = &c; >+ } >+ ++a; >+ } >+ return *d; >+} > > Jakub
--- gcc/tree-loop-distribution.c.jj 2017-12-21 09:43:17.486071696 +0100 +++ gcc/tree-loop-distribution.c 2017-12-30 16:54:08.106143319 +0100 @@ -3103,7 +3103,7 @@ pass_loop_distribution::execute (functio checking_verify_loop_structure (); - return 0; + return changed ? TODO_cleanup_cfg : 0; } } // anon namespace --- gcc/testsuite/gcc.dg/pr83581.c.jj 2017-12-30 16:55:35.950164947 +0100 +++ gcc/testsuite/gcc.dg/pr83581.c 2017-12-30 16:55:17.520160406 +0100 @@ -0,0 +1,21 @@ +/* PR tree-optimization/83581 */ +/* { dg-do compile } */ +/* { dg-options "-O3 -fno-tree-copy-prop -fno-tree-loop-im" } */ + +int a, b, c; + +int +foo (int x) +{ + int *d = &x; + while (a < 1) + { + for (b = 0; b < 2; ++b) + { + *d += !!x + 1; + d = &c; + } + ++a; + } + return *d; +}