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tree-optimization/103345: Improved load merging.

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This patch implements PR tree-optimization/103345 to merge adjacent
loads when combined with addition or bitwise xor.  The current code
in gimple-ssa-store-merging.c's find_bswap_or_nop alreay handles ior,
so that all that's required is to treat PLUS_EXPR and BIT_XOR_EXPR in
the same way at BIT_IOR_EXPR.  Many thanks to Andrew Pinski for
pointing out that this also resolves PR target/98953.

2021-11-22  Roger Sayle  <roger@nextmovesoftware.com>

gcc/ChangeLog
	PR tree-optimization/98953
	PR tree-optimization/103345
	* gimple-ssa-store-merging.c (find_bswap_or_nop_1): Handle
	BIT_XOR_EXPR and PLUS_EXPR the same as BIT_IOR_EXPR.
	(pass_optimize_bswap::execute): Likewise.

gcc/testsuite/ChangeLog
	PR tree-optimization/98953
	PR tree-optimization/103345
	* gcc.dg/tree-ssa/pr98953.c: New test case.
	* gcc.dg/tree-ssa/pr103345.c: New test case.
This commit is contained in:
Roger Sayle 2021-11-22 18:15:36 +00:00
parent c38c547a70
commit a944b5dec3
3 changed files with 72 additions and 4 deletions
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9
gcc/gimple-ssa-store-merging.c
View file

@ -742,10 +742,7 @@ find_bswap_or_nop_1 (gimple *stmt, struct symbolic_number *n, int limit)
struct symbolic_number n1, n2;
gimple *source_stmt, *source_stmt2;
if (code != BIT_IOR_EXPR)
return NULL;
if (TREE_CODE (rhs2) != SSA_NAME)
if (!rhs2 || TREE_CODE (rhs2) != SSA_NAME)
return NULL;
rhs2_stmt = SSA_NAME_DEF_STMT (rhs2);
@ -753,6 +750,8 @@ find_bswap_or_nop_1 (gimple *stmt, struct symbolic_number *n, int limit)
switch (code)
{
case BIT_IOR_EXPR:
case BIT_XOR_EXPR:
case PLUS_EXPR:
source_stmt1 = find_bswap_or_nop_1 (rhs1_stmt, &n1, limit - 1);
if (!source_stmt1)
@ -1495,6 +1494,8 @@ pass_optimize_bswap::execute (function *fun)
continue;
/* Fall through. */
case BIT_IOR_EXPR:
case BIT_XOR_EXPR:
case PLUS_EXPR:
break;
case CONSTRUCTOR:
{

53
gcc/testsuite/gcc.dg/tree-ssa/pr103345.c Normal file
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@ -0,0 +1,53 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-bswap-details" } */
typedef unsigned int uint32_t;
typedef unsigned char uint8_t;
uint32_t load_le_32_or(const uint8_t *ptr)
{
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
return ((uint32_t)ptr[0]) |
((uint32_t)ptr[1] << 8) |
((uint32_t)ptr[2] << 16) |
((uint32_t)ptr[3] << 24);
#else
return ((uint32_t)ptr[3]) |
((uint32_t)ptr[2] << 8) |
((uint32_t)ptr[1] << 16) |
((uint32_t)ptr[0] << 24);
#endif
}
uint32_t load_le_32_add(const uint8_t *ptr)
{
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
return ((uint32_t)ptr[0]) +
((uint32_t)ptr[1] << 8) +
((uint32_t)ptr[2] << 16) +
((uint32_t)ptr[3] << 24);
#else
return ((uint32_t)ptr[3]) +
((uint32_t)ptr[2] << 8) +
((uint32_t)ptr[1] << 16) +
((uint32_t)ptr[0] << 24);
#endif
}
uint32_t load_le_32_xor(const uint8_t *ptr)
{
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
return ((uint32_t)ptr[0]) ^
((uint32_t)ptr[1] << 8) ^
((uint32_t)ptr[2] << 16) ^
((uint32_t)ptr[3] << 24);
#else
return ((uint32_t)ptr[0]) ^
((uint32_t)ptr[1] << 8) ^
((uint32_t)ptr[2] << 16) ^
((uint32_t)ptr[3] << 24);
#endif
}
/* { dg-final { scan-tree-dump-times "32 bit load in target endianness found" 3 "bswap" } } */

14
gcc/testsuite/gcc.dg/tree-ssa/pr98953.c Normal file
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@ -0,0 +1,14 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-bswap-details" } */
int foo(unsigned char *ptr)
{
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
return ptr[0] + (ptr[1] << 8);
#else
return ptr[1] + (ptr[0] << 8);
#endif
}
/* { dg-final { scan-tree-dump "16 bit load in target endianness found" "bswap" } } */