https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111916
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jamborm at gcc dot gnu.org
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
ESRA does
int main ()
{
+ unsigned char g;
struct A g;
unsigned char _1;
unsigned char _2;
<bb 2> :
g = *.LC0;
+ g_6 = BIT_FIELD_REF <*.LC0, 8, 0>;
goto <bb 4>; [INV]
<bb 3> :
+ BIT_FIELD_REF <g, 8, 0> = g_6;
f = g;
<bb 4> :
- _1 = BIT_FIELD_REF <g, 8, 0>;
+ _1 = g_6;
_2 = _1 & 15;
if (_2 == 0)
goto <bb 3>; [INV]
which looks OK, but then SRA does
+ unsigned char SR.5;
+ unsigned char g;
unsigned char g;
struct A g;
unsigned char _1;
unsigned char _11;
<bb 2> [local count: 118111600]:
+ SR.5_10 = SR.5_2(D);
g = *.LC0;
- g_5 = BIT_FIELD_REF <*.LC0, 8, 0>;
+ g_14 = SR.5_10;
+ g_5 = SR.5_10;
_11 = g_5 & 15;
if (_11 == 0)
goto <bb 3>; [0.00%]
@@ -19,6 +33,8 @@
<bb 3> [local count: 955630224]:
BIT_FIELD_REF <g, 8, 0> = g_5;
+ g_16 = MEM <unsigned char> [(struct A *)&g];
+ MEM <unsigned char> [(struct A *)&g] = g_16;
f = g;
_1 = g_5 & 15;
goto <bb 3>; [100.00%]
which looks weird. First initialize_constant_pool_replacements inserts
SR.5 = BIT_FIELD_REF <*.LC0, 8, 0>;
which loosk OK, but then sra_modify_assign wrecks this, replacing the RHS
with 'SR.5', yielding
SR.5 = SR.5
this happens before the
/* Avoid modifying initializations of constant-pool replacements. */
if (racc && (racc->replacement_decl == lhs))
return SRA_AM_NONE;
code.
I can paper over with the following, but I wonder if sra_modify_expr needs
that very same check for constant-pool replacements?
diff --git a/gcc/tree-sra.cc b/gcc/tree-sra.cc
index f8dff8b27d7..efb52453250 100644
--- a/gcc/tree-sra.cc
+++ b/gcc/tree-sra.cc
@@ -4275,7 +4275,8 @@ sra_modify_assign (gimple *stmt, gimple_stmt_iterator
*gsi)
if (TREE_CODE (rhs) == REALPART_EXPR || TREE_CODE (lhs) == REALPART_EXPR
|| TREE_CODE (rhs) == IMAGPART_EXPR || TREE_CODE (lhs) == IMAGPART_EXPR
- || TREE_CODE (rhs) == BIT_FIELD_REF || TREE_CODE (lhs) == BIT_FIELD_REF)
+ || (TREE_CODE (rhs) == BIT_FIELD_REF && !sra_handled_bf_read_p (rhs))
+ || TREE_CODE (lhs) == BIT_FIELD_REF)
{
modify_this_stmt = sra_modify_expr (gimple_assign_rhs1_ptr (stmt),
gsi, false);
I will test this now.
