This makes VN not CSE .DEFERRED_INIT which confuses uninit
analysis which reports the wrong decl when facing copies
of not initialized data.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
2021-10-07 Richard Biener <rguent...@suse.de>
PR tree-optimization/102608
* tree-ssa-sccvn.c (visit_stmt): Drop .DEFERRED_INIT to
varying.
---
gcc/tree-ssa-sccvn.c | 45 +++++++++++++++++++++++---------------------
1 file changed, 24 insertions(+), 21 deletions(-)
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index 0d942218279..ae0172a143e 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -5668,27 +5668,30 @@ visit_stmt (gimple *stmt, bool backedges_varying_p =
false)
&& TREE_CODE (TREE_OPERAND (fn, 0)) == FUNCTION_DECL)
extra_fnflags = flags_from_decl_or_type (TREE_OPERAND (fn, 0));
}
- if (/* Calls to the same function with the same vuse
- and the same operands do not necessarily return the same
- value, unless they're pure or const. */
- ((gimple_call_flags (call_stmt) | extra_fnflags)
- & (ECF_PURE | ECF_CONST))
- /* If calls have a vdef, subsequent calls won't have
- the same incoming vuse. So, if 2 calls with vdef have the
- same vuse, we know they're not subsequent.
- We can value number 2 calls to the same function with the
- same vuse and the same operands which are not subsequent
- the same, because there is no code in the program that can
- compare the 2 values... */
- || (gimple_vdef (call_stmt)
- /* ... unless the call returns a pointer which does
- not alias with anything else. In which case the
- information that the values are distinct are encoded
- in the IL. */
- && !(gimple_call_return_flags (call_stmt) & ERF_NOALIAS)
- /* Only perform the following when being called from PRE
- which embeds tail merging. */
- && default_vn_walk_kind == VN_WALK))
+ if ((/* Calls to the same function with the same vuse
+ and the same operands do not necessarily return the same
+ value, unless they're pure or const. */
+ ((gimple_call_flags (call_stmt) | extra_fnflags)
+ & (ECF_PURE | ECF_CONST))
+ /* If calls have a vdef, subsequent calls won't have
+ the same incoming vuse. So, if 2 calls with vdef have the
+ same vuse, we know they're not subsequent.
+ We can value number 2 calls to the same function with the
+ same vuse and the same operands which are not subsequent
+ the same, because there is no code in the program that can
+ compare the 2 values... */
+ || (gimple_vdef (call_stmt)
+ /* ... unless the call returns a pointer which does
+ not alias with anything else. In which case the
+ information that the values are distinct are encoded
+ in the IL. */
+ && !(gimple_call_return_flags (call_stmt) & ERF_NOALIAS)
+ /* Only perform the following when being called from PRE
+ which embeds tail merging. */
+ && default_vn_walk_kind == VN_WALK))
+ /* Do not process .DEFERRED_INIT since that confuses uninit
+ analysis. */
+ && !gimple_call_internal_p (call_stmt, IFN_DEFERRED_INIT))
changed = visit_reference_op_call (lhs, call_stmt);
else
changed = defs_to_varying (call_stmt);
--
2.31.1
