The following adjusts costing of vector construction from scalars for
FP modes which with 387 math can reside in FP regs which need spilling
to be reloaded to XMM. I've played on the safe side with mixed
SSE/387 math.
Bootstrap and regtest running on x86_64-unknown-linux-gnu.
OK?
Thanks,
Richard.
PR target/121230
* config/i386/i386.cc (ix86_vector_costs::add_stmt_cost):
With FP mode and 387 math cost spill/reload.
* gcc.target/i386/pr121230.c: New testcase.
---
gcc/config/i386/i386.cc | 15 ++++++++++++++-
gcc/testsuite/gcc.target/i386/pr121230.c | 16 ++++++++++++++++
2 files changed, 30 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.target/i386/pr121230.c
diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index db43045753b..ad978d7474d 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -26397,7 +26397,20 @@ ix86_vector_costs::add_stmt_cost (int count,
vect_cost_for_stmt kind,
(TREE_OPERAND (gimple_assign_rhs1 (def), 0))))))
{
if (fp)
- m_num_sse_needed[where]++;
+ {
+ /* Scalar FP values residing in x87 registers need to be
+ spilled and reloaded. */
+ if (ix86_fpmath & FPMATH_387)
+ {
+ auto mode2 = TYPE_MODE (TREE_TYPE (op));
+ int cost
+ = (ix86_cost->hard_register.fp_store[mode2 == SFmode
+ ? 0 : 1]
+ + ix86_cost->sse_load[sse_store_index (mode2)]);
+ stmt_cost += COSTS_N_INSNS (cost) / 2;
+ }
+ m_num_sse_needed[where]++;
+ }
else
{
m_num_gpr_needed[where]++;
diff --git a/gcc/testsuite/gcc.target/i386/pr121230.c
b/gcc/testsuite/gcc.target/i386/pr121230.c
new file mode 100644
index 00000000000..67c9c5ccb2d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr121230.c
@@ -0,0 +1,16 @@
+/* { dg-do compile { target ia32 } } */
+/* { dg-options "-O3 -march=athlon-xp -mfpmath=387
-fexcess-precision=standard" } */
+
+typedef struct {
+ float a;
+ float b;
+} f32_2;
+
+f32_2 add32_2(f32_2 x, f32_2 y) {
+ return (f32_2){ x.a + y.a, x.b + y.b};
+}
+
+/* We do not want the vectorizer to vectorize the store and/or the
+ conversion (with IA32 we do not support V2SF add) given that spills
+ FP regs to reload them to XMM. */
+/* { dg-final { scan-assembler-not "movss\[ \\t\]+\[0-9\]*\\\(%esp\\\), %xmm"
} } */
--
2.51.0
