Hi:
As described in PR 39821, WIDEN_MULT_EXPR should use a different cost
model from MULT_EXPR, this patch add ix86_widen_mult_cost for that.
Reference basis for the cost model is https://godbolt.org/z/EMjaz4Knn.
Bootstrapped and regtested on x86_64-linux-gnu{-m32,}.
gcc/ChangeLog:
* config/i386/i386.c (ix86_widen_mult_cost): New function.
(ix86_add_stmt_cost): Use ix86_widen_mult_cost for
WIDEN_MULT_EXPR.
gcc/testsuite/ChangeLog:
* gcc.target/i386/sse2-pr39821.c: New test.
* gcc.target/i386/sse4-pr39821.c: New test.
---
gcc/config/i386/i386.c | 48 +++++++++++++++++++-
gcc/testsuite/gcc.target/i386/sse2-pr39821.c | 45 ++++++++++++++++++
gcc/testsuite/gcc.target/i386/sse4-pr39821.c | 4 ++
3 files changed, 96 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.target/i386/sse2-pr39821.c
create mode 100644 gcc/testsuite/gcc.target/i386/sse4-pr39821.c
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 876a19f4c1f..281b5fe2706 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -19757,6 +19757,44 @@ ix86_vec_cost (machine_mode mode, int cost)
return cost;
}
+/* Return cost of vec_widen_<s>mult_hi/lo_<mode>,
+ vec_widen_<s>mul_hi/lo_<mode> is only available for VI124_AVX2. */
+static int
+ix86_widen_mult_cost (const struct processor_costs *cost,
+ enum machine_mode mode, bool uns_p)
+{
+ gcc_assert (GET_MODE_CLASS (mode) == MODE_VECTOR_INT);
+ int extra_cost = 0;
+ int basic_cost = 0;
+ switch (mode)
+ {
+ case V8HImode:
+ case V16HImode:
+ if (!uns_p || mode == V16HImode)
+ extra_cost = cost->sse_op * 2;
+ basic_cost = cost->mulss * 2 + cost->sse_op * 4;
+ break;
+ case V4SImode:
+ case V8SImode:
+ /* pmulhw/pmullw can be used. */
+ basic_cost = cost->mulss * 2 + cost->sse_op * 2;
+ break;
+ case V2DImode:
+ /* pmuludq under sse2, pmuldq under sse4.1, for sign_extend,
+ require extra 4 mul, 4 add, 4 cmp and 2 shift. */
+ if (!TARGET_SSE4_1 && !uns_p)
+ extra_cost = (cost->mulss + cost->addss + cost->sse_op) * 4
+ + cost->sse_op * 2;
+ /* Fallthru. */
+ case V4DImode:
+ basic_cost = cost->mulss * 2 + cost->sse_op * 4;
+ break;
+ default:
+ gcc_unreachable();
+ }
+ return ix86_vec_cost (mode, basic_cost + extra_cost);
+}
+
/* Return cost of multiplication in MODE. */
static int
@@ -22483,10 +22521,18 @@ ix86_add_stmt_cost (class vec_info *vinfo, void
*data, int count,
break;
case MULT_EXPR:
- case WIDEN_MULT_EXPR:
+ /*For MULT_HIGHPART_EXPR, x86 only supports pmulhw,
+ take it as MULT_EXPR. */
case MULT_HIGHPART_EXPR:
stmt_cost = ix86_multiplication_cost (ix86_cost, mode);
break;
+ /* There's no direct instruction for WIDEN_MULT_EXPR,
+ take emulation into account. */
+ case WIDEN_MULT_EXPR:
+ stmt_cost = ix86_widen_mult_cost (ix86_cost, mode,
+ TYPE_UNSIGNED (vectype));
+ break;
+
case NEGATE_EXPR:
if (SSE_FLOAT_MODE_P (mode) && TARGET_SSE_MATH)
stmt_cost = ix86_cost->sse_op;
diff --git a/gcc/testsuite/gcc.target/i386/sse2-pr39821.c
b/gcc/testsuite/gcc.target/i386/sse2-pr39821.c
new file mode 100644
index 00000000000..bcd4b772c98
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/sse2-pr39821.c
@@ -0,0 +1,45 @@
+/* { dg-do compile } */
+/* { dg-options "-msse2 -mno-sse4.1 -O3 -fdump-tree-vect-details" } */
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops in function" 5 "vect"
} } */
+#include<stdint.h>
+void
+vec_widen_smul8 (int16_t* __restrict v3, int8_t *v1, int8_t *v2, int order)
+{
+ while (order--)
+ *v3++ = (int16_t) *v1++ * *v2++;
+}
+
+void
+vec_widen_umul8(uint16_t* __restrict v3, uint8_t *v1, uint8_t *v2, int order)
+{
+ while (order--)
+ *v3++ = (uint16_t) *v1++ * *v2++;
+}
+
+void
+vec_widen_smul16(int32_t* __restrict v3, int16_t *v1, int16_t *v2, int order)
+{
+ while (order--)
+ *v3++ = (int32_t) *v1++ * *v2++;
+}
+
+void
+vec_widen_umul16(uint32_t* __restrict v3, uint16_t *v1, uint16_t *v2, int
order)
+{
+ while (order--)
+ *v3++ = (uint32_t) *v1++ * *v2++;
+}
+
+void
+vec_widen_smul32(int64_t* __restrict v3, int32_t *v1, int32_t *v2, int order)
+{
+ while (order--)
+ *v3++ = (int64_t) *v1++ * *v2++;
+}
+
+void
+vec_widen_umul32(uint64_t* __restrict v3, uint32_t *v1, uint32_t *v2, int
order)
+{
+ while (order--)
+ *v3++ = (uint64_t) *v1++ * *v2++;
+}
diff --git a/gcc/testsuite/gcc.target/i386/sse4-pr39821.c
b/gcc/testsuite/gcc.target/i386/sse4-pr39821.c
new file mode 100644
index 00000000000..4456c31e43e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/sse4-pr39821.c
@@ -0,0 +1,4 @@
+/* { dg-do compile } */
+/* { dg-options "-msse4.1 -O3 -fdump-tree-vect-details" } */
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops in function" 6
"vect"} } */
+#include "sse2-pr39821.c"
--
2.27.0
