Richard Sandiford <rdsandiford@googlemail.com> writes:
This patch handles multiplications using a single HWIxHWI->2HWI multiplication
on hosts that have one. This removes all uses of the slow (half-HWI) path
for insn-recog.ii. The slow path is still used 58 times for cp/parser.ii
and 168 times for fold-const.ii, but at that kind of level it shouldn't
matter much.
I followed Joseph's suggestion and reused longlong.h. I copied it from
libgcc rather than glibc since it seemed better for GCC to have a single
version across both gcc/ and libgcc/. I can put it in include/ if that
seems better.
I've committed the patch to move longlong.h to trunk and merged back
to the branch, so all that's left is the wide-int.cc patch. OK to install?
Thanks,
Richard
Index: gcc/wide-int.cc
===================================================================
--- gcc/wide-int.cc 2013-12-03 23:59:08.133658567 +0000
+++ gcc/wide-int.cc 2013-12-04 12:55:28.466895358 +0000
@@ -27,6 +27,16 @@ along with GCC; see the file COPYING3.
#include "tree.h"
#include "dumpfile.h"
+#if GCC_VERSION >= 3000
+#define W_TYPE_SIZE HOST_BITS_PER_WIDE_INT
+typedef unsigned HOST_HALF_WIDE_INT UHWtype;
+typedef unsigned HOST_WIDE_INT UWtype;
+typedef unsigned int UQItype __attribute__ ((mode (QI)));
+typedef unsigned int USItype __attribute__ ((mode (SI)));
+typedef unsigned int UDItype __attribute__ ((mode (DI)));
+#include "longlong.h"
+#endif
+
/* This is the maximal size of the buffer needed for dump. */
const unsigned int MAX_SIZE = (4 * (MAX_BITSIZE_MODE_ANY_INT / 4
+ (MAX_BITSIZE_MODE_ANY_INT
@@ -1255,8 +1265,8 @@ wi_pack (unsigned HOST_WIDE_INT *result,
record in *OVERFLOW whether the result overflowed. SGN controls
the signedness and is used to check overflow or if HIGH is set. */
unsigned int
-wi::mul_internal (HOST_WIDE_INT *val, const HOST_WIDE_INT *op1,
- unsigned int op1len, const HOST_WIDE_INT *op2,
+wi::mul_internal (HOST_WIDE_INT *val, const HOST_WIDE_INT *op1val,
+ unsigned int op1len, const HOST_WIDE_INT *op2val,
unsigned int op2len, unsigned int prec, signop sgn,
bool *overflow, bool high)
{
@@ -1285,24 +1295,53 @@ wi::mul_internal (HOST_WIDE_INT *val, co
if (needs_overflow)
*overflow = false;
+ wide_int_ref op1 = wi::storage_ref (op1val, op1len, prec);
+ wide_int_ref op2 = wi::storage_ref (op2val, op2len, prec);
+
/* This is a surprisingly common case, so do it first. */
- if ((op1len == 1 && op1[0] == 0) || (op2len == 1 && op2[0] == 0))
+ if (op1 == 0 || op2 == 0)
{
val[0] = 0;
return 1;
}
+#ifdef umul_ppmm
+ if (sgn == UNSIGNED)
+ {
+ /* If the inputs are single HWIs and the output has room for at
+ least two HWIs, we can use umul_ppmm directly. */
+ if (prec >= HOST_BITS_PER_WIDE_INT * 2
+ && wi::fits_uhwi_p (op1)
+ && wi::fits_uhwi_p (op2))
+ {
+ umul_ppmm (val[1], val[0], op1.ulow (), op2.ulow ());
+ return 1 + (val[1] != 0 || val[0] < 0);
+ }
+ /* Likewise if the output is a full single HWI, except that the
+ upper HWI of the result is only used for determining overflow.
+ (We handle this case inline when overflow isn't needed.) */
+ else if (prec == HOST_BITS_PER_WIDE_INT)
+ {
+ unsigned HOST_WIDE_INT upper;
+ umul_ppmm (upper, val[0], op1.ulow (), op2.ulow ());
+ if (needs_overflow)
+ *overflow = (upper != 0);
+ return 1;
+ }
+ }
+#endif
+
/* Handle multiplications by 1. */
- if (op1len == 1 && op1[0] == 1)
+ if (op1 == 1)
{
for (i = 0; i < op2len; i++)
- val[i] = op2[i];
+ val[i] = op2val[i];
return op2len;
}
- if (op2len == 1 && op2[0] == 1)
+ if (op2 == 1)
{
for (i = 0; i < op1len; i++)
- val[i] = op1[i];
+ val[i] = op1val[i];
return op1len;
}
@@ -1316,13 +1355,13 @@ wi::mul_internal (HOST_WIDE_INT *val, co
if (sgn == SIGNED)
{
- o0 = sext_hwi (op1[0], prec);
- o1 = sext_hwi (op2[0], prec);
+ o0 = op1.to_shwi ();
+ o1 = op2.to_shwi ();
}
else
{
- o0 = zext_hwi (op1[0], prec);
- o1 = zext_hwi (op2[0], prec);
+ o0 = op1.to_uhwi ();
+ o1 = op2.to_uhwi ();
}
r = o0 * o1;
@@ -1344,9 +1383,9 @@ wi::mul_internal (HOST_WIDE_INT *val, co
}
/* We do unsigned mul and then correct it. */
- wi_unpack (u, (const unsigned HOST_WIDE_INT*)op1, op1len,
+ wi_unpack (u, (const unsigned HOST_WIDE_INT *) op1val, op1len,
half_blocks_needed, prec, SIGNED);
- wi_unpack (v, (const unsigned HOST_WIDE_INT*)op2, op2len,
+ wi_unpack (v, (const unsigned HOST_WIDE_INT *) op2val, op2len,
half_blocks_needed, prec, SIGNED);
/* The 2 is for a full mult. */
@@ -1371,7 +1410,7 @@ wi::mul_internal (HOST_WIDE_INT *val, co
if (sgn == SIGNED && (high || needs_overflow))
{
unsigned HOST_WIDE_INT b;
- if (op1[op1len-1] < 0)
+ if (wi::neg_p (op1))
{
b = 0;
for (i = 0; i < half_blocks_needed; i++)
@@ -1382,7 +1421,7 @@ wi::mul_internal (HOST_WIDE_INT *val, co
b = t >> (HOST_BITS_PER_WIDE_INT - 1);
}
}
- if (op2[op2len-1] < 0)
+ if (wi::neg_p (op2))
{
b = 0;
for (i = 0; i < half_blocks_needed; i++)