[COMMITTED/13] Fix PR 110386: backprop vs ABSU_EXPR

[COMMITTED/13] Fix PR 110386: backprop vs ABSU_EXPR

[Andrew Pinski]

From: Andrew Pinski <apinski@marvell.com>

The issue here is that when backprop tries to go
and strip sign ops, it skips over ABSU_EXPR but
ABSU_EXPR not only does an ABS, it also changes the
type to unsigned.
Since strip_sign_op_1 is only supposed to strip off
sign changing operands and not ones that change types,
removing ABSU_EXPR here is correct. We don't handle
nop conversions so this does cause any missed optimizations either.

Committed to the GCC 13 branch after bootstrapped and
tested on x86_64-linux-gnu with no regressions.

	PR tree-optimization/110386

gcc/ChangeLog:

	* gimple-ssa-backprop.cc (strip_sign_op_1): Remove ABSU_EXPR.

gcc/testsuite/ChangeLog:

	* gcc.c-torture/compile/pr110386-1.c: New test.
	* gcc.c-torture/compile/pr110386-2.c: New test.

(cherry picked from commit 2bbac12ea7bd8a3eef5382e1b13f6019df4ec03f)
---
 gcc/gimple-ssa-backprop.cc                       |  1 -
 gcc/testsuite/gcc.c-torture/compile/pr110386-1.c |  9 +++++++++
 gcc/testsuite/gcc.c-torture/compile/pr110386-2.c | 11 +++++++++++
 3 files changed, 20 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.c-torture/compile/pr110386-1.c
 create mode 100644 gcc/testsuite/gcc.c-torture/compile/pr110386-2.c

diff --git a/gcc/gimple-ssa-backprop.cc b/gcc/gimple-ssa-backprop.cc
index 65a65590017..dcb15ed4f61 100644
--- a/gcc/gimple-ssa-backprop.cc
+++ b/gcc/gimple-ssa-backprop.cc
@@ -694,7 +694,6 @@ strip_sign_op_1 (tree rhs)
     switch (gimple_assign_rhs_code (assign))
       {
       case ABS_EXPR:
-      case ABSU_EXPR:
       case NEGATE_EXPR:
 	return gimple_assign_rhs1 (assign);
 
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr110386-1.c b/gcc/testsuite/gcc.c-torture/compile/pr110386-1.c
new file mode 100644
index 00000000000..4fcc977ad16
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr110386-1.c
@@ -0,0 +1,9 @@
+
+int f(int a)
+{
+        int c = c < 0 ? c : -c;
+        c = -c;
+        unsigned b =  c;
+        unsigned t = b*a;
+        return t*t;
+}
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr110386-2.c b/gcc/testsuite/gcc.c-torture/compile/pr110386-2.c
new file mode 100644
index 00000000000..c60e1b6994b
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr110386-2.c
@@ -0,0 +1,11 @@
+/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
+/* { dg-options "-mavx" } */
+
+#include <immintrin.h>
+
+__m128i do_stuff(__m128i XMM0) {
+	__m128i ABS0 = _mm_abs_epi32(XMM0);
+	__m128i MUL0 = _mm_mullo_epi32(ABS0, XMM0);
+	__m128i MUL1 = _mm_mullo_epi32(MUL0, MUL0);
+	return MUL1;
+}
-- 
2.39.3

Re: [COMMITTED/13] Fix PR 110386: backprop vs ABSU_EXPR

[Andrew Pinski]

On Sun, Oct 1, 2023 at 12:28 PM Andrew Pinski <pinskia@gmail.com> wrote:
>
> From: Andrew Pinski <apinski@marvell.com>
>
> The issue here is that when backprop tries to go
> and strip sign ops, it skips over ABSU_EXPR but
> ABSU_EXPR not only does an ABS, it also changes the
> type to unsigned.
> Since strip_sign_op_1 is only supposed to strip off
> sign changing operands and not ones that change types,
> removing ABSU_EXPR here is correct. We don't handle
> nop conversions so this does cause any missed optimizations either.
>
> Committed to the GCC 13 branch after bootstrapped and
> tested on x86_64-linux-gnu with no regressions.

And to the GCC 12 and 11 branches too.

Thanks,
Andrew

>
>         PR tree-optimization/110386
>
> gcc/ChangeLog:
>
>         * gimple-ssa-backprop.cc (strip_sign_op_1): Remove ABSU_EXPR.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.c-torture/compile/pr110386-1.c: New test.
>         * gcc.c-torture/compile/pr110386-2.c: New test.
>
> (cherry picked from commit 2bbac12ea7bd8a3eef5382e1b13f6019df4ec03f)
> ---
>  gcc/gimple-ssa-backprop.cc                       |  1 -
>  gcc/testsuite/gcc.c-torture/compile/pr110386-1.c |  9 +++++++++
>  gcc/testsuite/gcc.c-torture/compile/pr110386-2.c | 11 +++++++++++
>  3 files changed, 20 insertions(+), 1 deletion(-)
>  create mode 100644 gcc/testsuite/gcc.c-torture/compile/pr110386-1.c
>  create mode 100644 gcc/testsuite/gcc.c-torture/compile/pr110386-2.c
>
> diff --git a/gcc/gimple-ssa-backprop.cc b/gcc/gimple-ssa-backprop.cc
> index 65a65590017..dcb15ed4f61 100644
> --- a/gcc/gimple-ssa-backprop.cc
> +++ b/gcc/gimple-ssa-backprop.cc
> @@ -694,7 +694,6 @@ strip_sign_op_1 (tree rhs)
>      switch (gimple_assign_rhs_code (assign))
>        {
>        case ABS_EXPR:
> -      case ABSU_EXPR:
>        case NEGATE_EXPR:
>         return gimple_assign_rhs1 (assign);
>
> diff --git a/gcc/testsuite/gcc.c-torture/compile/pr110386-1.c b/gcc/testsuite/gcc.c-torture/compile/pr110386-1.c
> new file mode 100644
> index 00000000000..4fcc977ad16
> --- /dev/null
> +++ b/gcc/testsuite/gcc.c-torture/compile/pr110386-1.c
> @@ -0,0 +1,9 @@
> +
> +int f(int a)
> +{
> +        int c = c < 0 ? c : -c;
> +        c = -c;
> +        unsigned b =  c;
> +        unsigned t = b*a;
> +        return t*t;
> +}
> diff --git a/gcc/testsuite/gcc.c-torture/compile/pr110386-2.c b/gcc/testsuite/gcc.c-torture/compile/pr110386-2.c
> new file mode 100644
> index 00000000000..c60e1b6994b
> --- /dev/null
> +++ b/gcc/testsuite/gcc.c-torture/compile/pr110386-2.c
> @@ -0,0 +1,11 @@
> +/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
> +/* { dg-options "-mavx" } */
> +
> +#include <immintrin.h>
> +
> +__m128i do_stuff(__m128i XMM0) {
> +       __m128i ABS0 = _mm_abs_epi32(XMM0);
> +       __m128i MUL0 = _mm_mullo_epi32(ABS0, XMM0);
> +       __m128i MUL1 = _mm_mullo_epi32(MUL0, MUL0);
> +       return MUL1;
> +}
> --
> 2.39.3
>