aarch64: Make aarch64_add_offset work with -ftrapv [PR99540]

aarch64_add_offset uses expand_mult to multiply the SVE VL by an
out-of-range constant.  expand_mult takes an argument to indicate
whether the multiplication is signed or unsigned, but in this
context the multiplication is effectively signless and so the
choice seemed arbitrary.

However, one of the things that the signedness input does is
indicate whether signed overflow should be trapped for -ftrapv.
We don't want that here, so we must treat the multiplication
as unsigned.

gcc/
2021-03-23  Jakub Jelinek  <jakub@redhat.com>

	PR target/99540
	* config/aarch64/aarch64.c (aarch64_add_offset): Tell
	expand_mult to perform an unsigned rather than a signed
	multiplication.

gcc/testsuite/
2021-03-23  Richard Sandiford  <richard.sandiford@arm.com>

	PR target/99540
	* gcc.dg/vect/pr99540.c: New test.

diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index db69e6983d0b4f6505e84c43090193cb70674881..c8a87fe858a3c53c3d863361ccdc05d20ac4798c 100644 (file)
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -4639,7 +4639,7 @@ aarch64_add_offset (scalar_int_mode mode, rtx dest, rtx src,
          if (can_create_pseudo_p ())
            {
              rtx coeff1 = gen_int_mode (factor, mode);
-             val = expand_mult (mode, val, coeff1, NULL_RTX, false, true);
+             val = expand_mult (mode, val, coeff1, NULL_RTX, true, true);
            }
          else
            {

diff --git a/gcc/testsuite/gcc.dg/vect/pr99540.c b/gcc/testsuite/gcc.dg/vect/pr99540.c
new file mode 100644 (file)
index 0000000..9136b09
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr99540.c
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-ftrapv -ffloat-store -march=armv8.2-a+sve" { target aarch64*-*-* } } */
+
+float *MSalign2m2m_rec_initverticalw, *MSalign2m2m_rec_currentw;
+
+void
+match_ribosum (int MSalign2m2m_rec_i, int MSalign2m2m_rec_lgth1,
+               int MSalign2m2m_rec_lgth2)
+{
+  float **WMMTX;
+
+  while (MSalign2m2m_rec_i < 1)
+    WMMTX[MSalign2m2m_rec_i++][0] = MSalign2m2m_rec_initverticalw[0];
+
+  while (MSalign2m2m_rec_i < MSalign2m2m_rec_lgth1)
+    MSalign2m2m_rec_initverticalw[MSalign2m2m_rec_i++] += 0.1;
+
+  while (MSalign2m2m_rec_i < MSalign2m2m_rec_lgth2)
+    MSalign2m2m_rec_currentw[MSalign2m2m_rec_i++] += 0.1;
+}