[PATCH, rs6000] Disable gimple fold for float or double vec_minmax when fast-math is not set

HAO CHEN GUI guihaoc@linux.ibm.com
Wed Aug 25 07:06:59 GMT 2021


Hi,

     I refined the patch according to Bill's advice. I pasted the 
ChangeLog and diff file here. If it doesn't work, please let me know. 
Thanks.

2021-08-25 Haochen Gui <guihaoc@linux.ibm.com>

gcc/
     * config/rs6000/rs6000-call.c (rs6000_gimple_fold_builtin):
     Modify the VSX_BUILTIN_XVMINDP, ALTIVEC_BUILTIN_VMINFP,
     VSX_BUILTIN_XVMAXDP, ALTIVEC_BUILTIN_VMAXFP expansions.

gcc/testsuite/
     * gcc.target/powerpc/vec-minmax-1.c: New test.
     * gcc.target/powerpc/vec-minmax-2.c: Likewise.

diff --git a/gcc/config/rs6000/rs6000-call.c 
b/gcc/config/rs6000/rs6000-call.c
index b4e13af4dc6..90527734ceb 100644
--- a/gcc/config/rs6000/rs6000-call.c
+++ b/gcc/config/rs6000/rs6000-call.c
@@ -12159,6 +12159,11 @@ rs6000_gimple_fold_builtin 
(gimple_stmt_iterator *gsi)
        return true;
      /* flavors of vec_min.  */
      case VSX_BUILTIN_XVMINDP:
+    case ALTIVEC_BUILTIN_VMINFP:
+      if (!flag_finite_math_only || flag_signed_zeros)
+    return false;
+      /* Fall through to MIN_EXPR.  */
+      gcc_fallthrough ();
      case P8V_BUILTIN_VMINSD:
      case P8V_BUILTIN_VMINUD:
      case ALTIVEC_BUILTIN_VMINSB:
@@ -12167,7 +12172,6 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator 
*gsi)
      case ALTIVEC_BUILTIN_VMINUB:
      case ALTIVEC_BUILTIN_VMINUH:
      case ALTIVEC_BUILTIN_VMINUW:
-    case ALTIVEC_BUILTIN_VMINFP:
        arg0 = gimple_call_arg (stmt, 0);
        arg1 = gimple_call_arg (stmt, 1);
        lhs = gimple_call_lhs (stmt);
@@ -12177,6 +12181,11 @@ rs6000_gimple_fold_builtin 
(gimple_stmt_iterator *gsi)
        return true;
      /* flavors of vec_max.  */
      case VSX_BUILTIN_XVMAXDP:
+    case ALTIVEC_BUILTIN_VMAXFP:
+      if (!flag_finite_math_only || flag_signed_zeros)
+    return false;
+      /* Fall through to MAX_EXPR.  */
+      gcc_fallthrough ();
      case P8V_BUILTIN_VMAXSD:
      case P8V_BUILTIN_VMAXUD:
      case ALTIVEC_BUILTIN_VMAXSB:
@@ -12185,7 +12194,6 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator 
*gsi)
      case ALTIVEC_BUILTIN_VMAXUB:
      case ALTIVEC_BUILTIN_VMAXUH:
      case ALTIVEC_BUILTIN_VMAXUW:
-    case ALTIVEC_BUILTIN_VMAXFP:
        arg0 = gimple_call_arg (stmt, 0);
        arg1 = gimple_call_arg (stmt, 1);
        lhs = gimple_call_lhs (stmt);
diff --git a/gcc/testsuite/gcc.target/powerpc/vec-minmax-1.c 
b/gcc/testsuite/gcc.target/powerpc/vec-minmax-1.c
new file mode 100644
index 00000000000..da92f059aea
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/vec-minmax-1.c
@@ -0,0 +1,53 @@
+/* { dg-do compile { target { powerpc64le-*-* } } } */
+/* { dg-require-effective-target powerpc_p9vector_ok } */
+/* { dg-options "-O2 -mdejagnu-cpu=power9" } */
+/* { dg-final { scan-assembler-times {\mxvmaxdp\M} 1 } } */
+/* { dg-final { scan-assembler-times {\mxvmaxsp\M} 1 } } */
+/* { dg-final { scan-assembler-times {\mxvmindp\M} 1 } } */
+/* { dg-final { scan-assembler-times {\mxvminsp\M} 1 } } */
+
+/* This test verifies that float or double vec_min/max are bound to
+   xv[min|max][d|s]p instructions when fast-math is not set.  */
+
+
+#include <altivec.h>
+
+#ifdef _BIG_ENDIAN
+   const int PREF_D = 0;
+#else
+   const int PREF_D = 1;
+#endif
+
+double vmaxd (double a, double b)
+{
+  vector double va = vec_promote (a, PREF_D);
+  vector double vb = vec_promote (b, PREF_D);
+  return vec_extract (vec_max (va, vb), PREF_D);
+}
+
+double vmind (double a, double b)
+{
+  vector double va = vec_promote (a, PREF_D);
+  vector double vb = vec_promote (b, PREF_D);
+  return vec_extract (vec_min (va, vb), PREF_D);
+}
+
+#ifdef _BIG_ENDIAN
+   const int PREF_F = 0;
+#else
+   const int PREF_F = 3;
+#endif
+
+float vmaxf (float a, float b)
+{
+  vector float va = vec_promote (a, PREF_F);
+  vector float vb = vec_promote (b, PREF_F);
+  return vec_extract (vec_max (va, vb), PREF_F);
+}
+
+float vminf (float a, float b)
+{
+  vector float va = vec_promote (a, PREF_F);
+  vector float vb = vec_promote (b, PREF_F);
+  return vec_extract (vec_min (va, vb), PREF_F);
+}
diff --git a/gcc/testsuite/gcc.target/powerpc/vec-minmax-2.c 
b/gcc/testsuite/gcc.target/powerpc/vec-minmax-2.c
new file mode 100644
index 00000000000..d318b933181
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/vec-minmax-2.c
@@ -0,0 +1,51 @@
+/* { dg-do compile { target { powerpc64le-*-* } } } */
+/* { dg-require-effective-target powerpc_p9vector_ok } */
+/* { dg-options "-O2 -mdejagnu-cpu=power9 -ffast-math" } */
+/* { dg-final { scan-assembler-times {\mxsmaxcdp\M} 2 } } */
+/* { dg-final { scan-assembler-times {\mxsmincdp\M} 2 } } */
+
+/* This test verifies that float or double vec_min/max can be converted
+   to scalar comparison when fast-math is set.  */
+
+
+#include <altivec.h>
+
+#ifdef _BIG_ENDIAN
+   const int PREF_D = 0;
+#else
+   const int PREF_D = 1;
+#endif
+
+double vmaxd (double a, double b)
+{
+  vector double va = vec_promote (a, PREF_D);
+  vector double vb = vec_promote (b, PREF_D);
+  return vec_extract (vec_max (va, vb), PREF_D);
+}
+
+double vmind (double a, double b)
+{
+  vector double va = vec_promote (a, PREF_D);
+  vector double vb = vec_promote (b, PREF_D);
+  return vec_extract (vec_min (va, vb), PREF_D);
+}
+
+#ifdef _BIG_ENDIAN
+   const int PREF_F = 0;
+#else
+   const int PREF_F = 3;
+#endif
+
+float vmaxf (float a, float b)
+{
+  vector float va = vec_promote (a, PREF_F);
+  vector float vb = vec_promote (b, PREF_F);
+  return vec_extract (vec_max (va, vb), PREF_F);
+}
+
+float vminf (float a, float b)
+{
+  vector float va = vec_promote (a, PREF_F);
+  vector float vb = vec_promote (b, PREF_F);
+  return vec_extract (vec_min (va, vb), PREF_F);
+}

On 25/8/2021 上午 6:40, Segher Boessenkool wrote:
> Hi!
>
> On Tue, Aug 24, 2021 at 03:04:26PM -0500, Bill Schmidt wrote:
>> On 8/24/21 3:52 AM, HAO CHEN GUI wrote:
>> Thanks for this patch!  In the future, if you can put your ChangeLog and
>> patch inline in your post, it makes it easier to review.  (Otherwise we
>> have to manually copy it into our response and manipulate it to look
>> quoted, etc.)
> It is encoded even, making it impossible to easily apply the patch, etc.
>
>>> diff --git a/gcc/config/rs6000/rs6000-call.c
>>> b/gcc/config/rs6000/rs6000-call.c index b4e13af4dc6..90527734ceb
>>> 100644 --- a/gcc/config/rs6000/rs6000-call.c +++
>>> b/gcc/config/rs6000/rs6000-call.c @@ -12159,6 +12159,11 @@
>>> rs6000_gimple_fold_builtin (gimple_stmt_iterator *gsi) return true; /*
>>> flavors of vec_min. */ case VSX_BUILTIN_XVMINDP: + case
> format=flawed :-(
>
>
> Segher


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