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| author | law <law@138bc75d-0d04-0410-961f-82ee72b054a4> | 2005-12-16 07:03:12 +0000 |
|---|---|---|
| committer | law <law@138bc75d-0d04-0410-961f-82ee72b054a4> | 2005-12-16 07:03:12 +0000 |
| commit | 2b9070b6074f3138196132879507cab903308feb (patch) | |
| tree | 88a7799c9f4d7f31317de3ae132949f5dde781d1 /gcc | |
| parent | c4503c0a24b13382f88c58711cf142064ec51e26 (diff) | |
| download | gcc-2b9070b6074f3138196132879507cab903308feb.tar.gz | |
* tree-ssa-dse.c (dse_optimize_stmt): Correctly handle PHI nodes which
represent a use and definition of the same SSA_NAME.
* gcc.dg/tree-ssa/ssa-dse-8.c: New test.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@108630 138bc75d-0d04-0410-961f-82ee72b054a4
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/testsuite/ChangeLog | 4 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-8.c | 26 | ||||
| -rw-r--r-- | gcc/tree-ssa-dse.c | 9 |
4 files changed, 44 insertions, 0 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 661e5337a53..d90de63c4a9 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2005-12-16 Jeff Law <law@redhat.com> + + * tree-ssa-dse.c (dse_optimize_stmt): Correctly handle PHI nodes which + represent a use and definition of the same SSA_NAME. + 2005-12-16 Jon Grimm <jgrimm2@us.ibm.com> Janis Johnson <janis187@us.ibm.com> Ben Elliston <bje@au.ibm.com> diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 6662c2eaffa..9c4ba84cbe3 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2005-12-16 Jeff Law <law@redhat.com> + + * gcc.dg/tree-ssa/ssa-dse-8.c: New test. + 2005-12-16 Andrew Pinski <pinskia@physics.uc.edu> * objc.dg/gnu-encoding/struct-layout-encoding-1_generate.c (base_types): diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-8.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-8.c new file mode 100644 index 00000000000..de1d5bb6240 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-8.c @@ -0,0 +1,26 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fno-tree-dce -fno-tree-ccp -fno-tree-copy-prop -fno-tree-dominator-opts" } */ + +/* This caused the compiler to enter an infinite loop if copies are not + fully propagated. The options are to disable copy propagation and + thus expose the bug. */ + +int foo (void); + +struct A { + struct B { + struct B *n; + } *p; +}; + +static inline void baz (struct A *a) +{ + a->p = a->p->n; +} + +void bar (struct A a) +{ + while (foo ()) + baz (&a); + while (foo ()); +} diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c index fa3ba960a28..f1cc22ae310 100644 --- a/gcc/tree-ssa-dse.c +++ b/gcc/tree-ssa-dse.c @@ -309,6 +309,15 @@ dse_optimize_stmt (struct dom_walk_data *walk_data, && TREE_CODE (use_stmt) == PHI_NODE && bitmap_bit_p (dse_gd->stores, get_stmt_uid (use_stmt))) { + /* A PHI node can both define and use the same SSA_NAME if + the PHI is at the top of a loop and the PHI_RESULT is + a loop invariant and copies have not been fully propagated. + + The safe thing to do is exit assuming no optimization is + possible. */ + if (SSA_NAME_DEF_STMT (PHI_RESULT (use_stmt)) == use_stmt) + return; + /* Skip past this PHI and loop again in case we had a PHI chain. */ if (single_imm_use (PHI_RESULT (use_stmt), &use_p, &use_stmt)) |