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2014-11-12  Thomas Preud'homme  <thomas.preudhomme@arm.com>

    gcc/
    PR tree-optimization/63761
    * tree-ssa-math-opts.c (bswap_replace): Construct gsi from cur_stmt
    rather than taking it as a parameter. Add some comments to explain the
    gsi_move_before in case of load and why canonicalization of bswap into
    a rotation is only done for 16bit values.
    (pass_optimize_bswap::execute): Adapt for loop via gsi to make gsi
    refer to the statement just before cur_stmt. Ignore 16bit bswap that
    are already in canonical form. Adapt bswap_replace to removal of its
    gsi parameter.

    2014-11-12  Thomas Preud'homme  <thomas.preudhomme@arm.com>

    gcc/testsuite/
    PR tree-optimization/63761
    * gcc.c-torture/compile/pr63761.c: New test.

From-SVN: r217409
This commit is contained in:
Thomas Preud'homme 2014-11-12 09:50:20 +00:00 committed by Thomas Preud'homme
parent d30fc980ac
commit f351abd679
4 changed files with 74 additions and 18 deletions
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12
gcc/ChangeLog
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@ -1,3 +1,15 @@
2014-11-12 Thomas Preud'homme <thomas.preudhomme@arm.com>
PR tree-optimization/63761
* tree-ssa-math-opts.c (bswap_replace): Construct gsi from cur_stmt
rather than taking it as a parameter. Add some comments to explain the
gsi_move_before in case of load and why canonicalization of bswap into
a rotation is only done for 16bit values.
(pass_optimize_bswap::execute): Adapt for loop via gsi to make gsi
refer to the statement just before cur_stmt. Ignore 16bit bswap that
are already in canonical form. Adapt bswap_replace to removal of its
gsi parameter.
2014-11-12 Richard Sandiford <richard.sandiford@arm.com>
* rtl.h (rtx_function, for_each_rtx, for_each_rtx_in_insn): Delete.

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2014-11-12 Thomas Preud'homme <thomas.preudhomme@arm.com>
PR tree-optimization/63761
* gcc.c-torture/compile/pr63761.c: New test.
2014-11-12 Jiong Wang <jiong.wang@arm.com>
* lib/gcc-dg.exp (${tool}_load): Truncate gcc output.

17
gcc/testsuite/gcc.c-torture/compile/pr63761.c Normal file
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@ -0,0 +1,17 @@
int a, b;
short c;
void fn1 ();
void
fn2 (unsigned short p1)
{
int d;
c = p1 >> 8 | p1 << 8;
d = b;
if (d)
fn1 ();
a = d >> 8 & 0x00FF
| d << 8 & 0xFF00;
}

58
gcc/tree-ssa-math-opts.c
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@ -2172,23 +2172,28 @@ public:
}; // class pass_optimize_bswap
/* Perform the bswap optimization: replace the statement CUR_STMT at
GSI with a load of type, VUSE and set-alias as described by N if a
memory source is involved (N->base_addr is non null), followed by
the builtin bswap invocation in FNDECL if BSWAP is true. SRC_STMT
gives where should the replacement be made. It also gives the
source on which CUR_STMT is operating via its rhs's first tree nad
N->range gives the size of the expression involved for maintaining
some statistics. */
/* Perform the bswap optimization: replace the expression computed in the rhs
of CUR_STMT by an equivalent bswap, load or load + bswap expression.
Which of these alternatives replace the rhs is given by N->base_addr (non
null if a load is needed) and BSWAP. The type, VUSE and set-alias of the
load to perform are also given in N while the builtin bswap invoke is given
in FNDEL. Finally, if a load is involved, SRC_STMT refers to one of the
load statements involved to construct the rhs in CUR_STMT and N->range gives
the size of the rhs expression for maintaining some statistics.
Note that if the replacement involve a load, CUR_STMT is moved just after
SRC_STMT to do the load with the same VUSE which can lead to CUR_STMT
changing of basic block. */
static bool
bswap_replace (gimple cur_stmt, gimple_stmt_iterator gsi, gimple src_stmt,
tree fndecl, tree bswap_type, tree load_type,
struct symbolic_number *n, bool bswap)
bswap_replace (gimple cur_stmt, gimple src_stmt, tree fndecl, tree bswap_type,
tree load_type, struct symbolic_number *n, bool bswap)
{
gimple_stmt_iterator gsi;
tree src, tmp, tgt;
gimple bswap_stmt;
gsi = gsi_for_stmt (cur_stmt);
src = gimple_assign_rhs1 (src_stmt);
tgt = gimple_assign_lhs (cur_stmt);
@ -2207,6 +2212,9 @@ bswap_replace (gimple cur_stmt, gimple_stmt_iterator gsi, gimple src_stmt,
&& SLOW_UNALIGNED_ACCESS (TYPE_MODE (load_type), align))
return false;
/* Move cur_stmt just before one of the load of the original
to ensure it has the same VUSE. See PR61517 for what could
go wrong. */
gsi_move_before (&gsi, &gsi_ins);
gsi = gsi_for_stmt (cur_stmt);
@ -2293,7 +2301,10 @@ bswap_replace (gimple cur_stmt, gimple_stmt_iterator gsi, gimple src_stmt,
tmp = src;
/* Canonical form for 16 bit bswap is a rotate expression. */
/* Canonical form for 16 bit bswap is a rotate expression. Only 16bit values
are considered as rotation of 2N bit values by N bits is generally not
equivalent to a bswap. Consider for instance 0x01020304 >> 16 which gives
0x03040102 while a bswap for that value is 0x04030201. */
if (bswap && n->range == 16)
{
tree count = build_int_cst (NULL, BITS_PER_UNIT);
@ -2393,10 +2404,10 @@ pass_optimize_bswap::execute (function *fun)
gimple_stmt_iterator gsi;
/* We do a reverse scan for bswap patterns to make sure we get the
widest match. As bswap pattern matching doesn't handle
previously inserted smaller bswap replacements as sub-
patterns, the wider variant wouldn't be detected. */
for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi_prev (&gsi))
widest match. As bswap pattern matching doesn't handle previously
inserted smaller bswap replacements as sub-patterns, the wider
variant wouldn't be detected. */
for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi);)
{
gimple src_stmt, cur_stmt = gsi_stmt (gsi);
tree fndecl = NULL_TREE, bswap_type = NULL_TREE, load_type;
@ -2404,6 +2415,14 @@ pass_optimize_bswap::execute (function *fun)
struct symbolic_number n;
bool bswap;
/* This gsi_prev (&gsi) is not part of the for loop because cur_stmt
might be moved to a different basic block by bswap_replace and gsi
must not points to it if that's the case. Moving the gsi_prev
there make sure that gsi points to the statement previous to
cur_stmt while still making sure that all statements are
considered in this basic block. */
gsi_prev (&gsi);
if (!is_gimple_assign (cur_stmt))
continue;
@ -2431,6 +2450,9 @@ pass_optimize_bswap::execute (function *fun)
switch (n.range)
{
case 16:
/* Already in canonical form, nothing to do. */
if (code == LROTATE_EXPR || code == RROTATE_EXPR)
continue;
load_type = uint16_type_node;
if (bswap16_p)
{
@ -2461,8 +2483,8 @@ pass_optimize_bswap::execute (function *fun)
if (bswap && !fndecl)
continue;
if (bswap_replace (cur_stmt, gsi, src_stmt, fndecl, bswap_type,
load_type, &n, bswap))
if (bswap_replace (cur_stmt, src_stmt, fndecl, bswap_type, load_type,
&n, bswap))
changed = true;
}
}