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| author | Richard Biener <rguenther@suse.de> | 2023-12-11 13:00:18 +0100 |
|---|---|---|
| committer | Richard Biener <rguenther@suse.de> | 2023-12-12 08:14:47 +0100 |
| commit | f5f33b44b5dd4c41ae335445ae3f06b1ca3cfbcb (patch) | |
| tree | 6a56de2ae1ff726e474ba8c8cbe6f3ed7354ff16 | |
| parent | fc62716fe8d1d60a9f1c6906e5a4845b3331b828 (diff) | |
| download | gcc-f5f33b44b5dd4c41ae335445ae3f06b1ca3cfbcb.zip gcc-f5f33b44b5dd4c41ae335445ae3f06b1ca3cfbcb.tar.gz gcc-f5f33b44b5dd4c41ae335445ae3f06b1ca3cfbcb.tar.bz2 | |
tree-optimization/112939 - VN PHI visiting and -ftrivial-auto-var-init
The following builds upon the last fix, making sure we only value-number
to visited (un-)defs, otherwise prefer .VN_TOP.
PR tree-optimization/112939
* tree-ssa-sccvn.cc (visit_phi): When all args are undefined
make sure we end up with a value that was visited, otherwise
fall back to .VN_TOP.
* gcc.dg/pr112939.c: New testcase.
| -rw-r--r-- | gcc/testsuite/gcc.dg/pr112939.c | 23 | ||||
| -rw-r--r-- | gcc/tree-ssa-sccvn.cc | 4 |
2 files changed, 26 insertions, 1 deletions
diff --git a/gcc/testsuite/gcc.dg/pr112939.c b/gcc/testsuite/gcc.dg/pr112939.c new file mode 100644 index 0000000..7017bef --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr112939.c @@ -0,0 +1,23 @@ +/* { dg-do compile } */ +/* { dg-options "-O -ftrivial-auto-var-init=zero" } */ + +int i; + +void f (void) +{ + for (;;) + { + if (0) + for (;;) + { + int *a; + int *b = a; + + l1: + *b = (*b != 0) ? 0 : 2; + } + + if (i != 0) + goto l1; + } +} diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc index 11537fa..a178b76 100644 --- a/gcc/tree-ssa-sccvn.cc +++ b/gcc/tree-ssa-sccvn.cc @@ -5946,6 +5946,8 @@ visit_phi (gimple *phi, bool *inserted, bool backedges_varying_p) if (TREE_CODE (def) == SSA_NAME) { tree val = SSA_VAL (def, &visited); + if (SSA_NAME_IS_DEFAULT_DEF (def)) + visited = true; if (!backedges_varying_p || !(e->flags & EDGE_DFS_BACK)) def = val; if (e->flags & EDGE_DFS_BACK) @@ -6091,7 +6093,7 @@ visit_phi (gimple *phi, bool *inserted, bool backedges_varying_p) /* If we saw only undefined values and VN_TOP use one of the undefined values. */ else if (sameval == VN_TOP) - result = seen_undef ? seen_undef : sameval; + result = (seen_undef && seen_undef_visited) ? seen_undef : sameval; /* First see if it is equivalent to a phi node in this block. We prefer this as it allows IV elimination - see PRs 66502 and 67167. */ else if ((result = vn_phi_lookup (phi, backedges_varying_p))) |