[gcc r17-2789] middle-end: fix COND_FMS foldings [PR126465]

https://gcc.gnu.org/g:e6e3290cddbf1da000bfc6fcd2a1e5a2b2cd27fb

commit r17-2789-ge6e3290cddbf1da000bfc6fcd2a1e5a2b2cd27fb
Author: Tamar Christina <[email protected]>
Date:   Wed Jul 29 14:16:52 2026 +0100

    middle-end: fix COND_FMS foldings [PR126465]
    
    in r16-6508-g772b847d99d5e3 I made some typos
    
    1. I forgot to negate the else value
    2. one of the patterns was missing the mask.
    
    This fixes it. The patterns moving the COND inwards are still useful because
    they allow FMA forwarding as most micro-architectures don't forward FMA when
    there's a random instruction like fneg in between.
    
    Sorry for the mistakes. I added more tests to cover these now.
    
    gcc/ChangeLog:
    
            PR tree-optimization/126465
            * match.pd: Fix FMS patterns.
    
    gcc/testsuite/ChangeLog:
    
            PR tree-optimization/126465
            * gcc.target/aarch64/sve/cond_fma.c: New test.
            * gcc.target/aarch64/sve/cond_fma_neg_addend.c: New test.
            * gcc.target/aarch64/sve/cond_fms.c: New test.
            * gcc.target/aarch64/sve/cond_fnma.c: New test.
            * gcc.target/aarch64/sve/cond_fnms.c: New test.

Diff:
---
 gcc/match.pd                                       | 12 +++----
 gcc/testsuite/gcc.target/aarch64/sve/cond_fma.c    | 37 ++++++++++++++++++++++
 .../gcc.target/aarch64/sve/cond_fma_neg_addend.c   | 34 ++++++++++++++++++++
 gcc/testsuite/gcc.target/aarch64/sve/cond_fms.c    | 37 ++++++++++++++++++++++
 gcc/testsuite/gcc.target/aarch64/sve/cond_fnma.c   | 37 ++++++++++++++++++++++
 gcc/testsuite/gcc.target/aarch64/sve/cond_fnms.c   | 37 ++++++++++++++++++++++
 6 files changed, 188 insertions(+), 6 deletions(-)

diff --git a/gcc/match.pd b/gcc/match.pd
index 6f2d96c034b4..ff5d012f7fd6 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -10334,14 +10334,14 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
    (IFN_COND_FNMA @3 @0 @1 @2 @4))
   (simplify
    (fmas @3 @0 @1 (negate @2) @4)
-   (IFN_COND_FMS @0 @1 @2 @4))
+   (IFN_COND_FMS @3 @0 @1 @2 @4))
   (simplify
    (fmas:c @3 (negate @0) @1 (negate @2) @4)
    (IFN_COND_FNMS @3 @0 @1 @2 @4))
   (simplify
    (negate (fmas@3 @4 @0 @1 @2 @5))
    (if (!HONOR_SIGN_DEPENDENT_ROUNDING (type) && single_use (@3))
-    (IFN_COND_FNMS @4 @0 @1 @2 @5))))
+    (IFN_COND_FNMS @4 @0 @1 @2 (negate @5)))))
 
  (simplify
   (IFN_COND_FMS:c @3 (negate @0) @1 @2 @4)
@@ -10353,9 +10353,9 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
   (IFN_COND_FMS:c @3 (negate @0) @1 (negate @2) @4)
   (IFN_COND_FNMA @3 @0 @1 @2 @4))
  (simplify
-  (negate (IFN_FMS@3 @4 @0 @1 @2 @5))
+  (negate (IFN_COND_FMS@3 @4 @0 @1 @2 @5))
    (if (!HONOR_SIGN_DEPENDENT_ROUNDING (type) && single_use (@3))
-    (IFN_COND_FNMA @4 @0 @1 @2 @5)))
+    (IFN_COND_FNMA @4 @0 @1 @2 (negate @5))))
 
  (simplify
   (IFN_COND_FNMA:c @3 (negate @0) @1 @2 @4)
@@ -10369,7 +10369,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  (simplify
   (negate (IFN_COND_FNMA@3 @4 @0 @1 @2 @5))
   (if (!HONOR_SIGN_DEPENDENT_ROUNDING (type) && single_use (@3))
-   (IFN_COND_FMS @4 @0 @1 @2 @5)))
+   (IFN_COND_FMS @4 @0 @1 @2 (negate @5))))
 
  (simplify
   (IFN_COND_FNMS:c @3 (negate @0) @1 @2 @4)
@@ -10383,7 +10383,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  (simplify
   (negate (IFN_COND_FNMS@3 @4 @0 @1 @2 @5))
   (if (!HONOR_SIGN_DEPENDENT_ROUNDING (type) && single_use (@3))
-   (IFN_COND_FMA @4 @0 @1 @2 @5))))
+   (IFN_COND_FMA @4 @0 @1 @2 (negate @5)))))
 
 /* CLZ simplifications.  */
 (for clz (CLZ)
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/cond_fma.c b/gcc/testsuite/gcc.target/aarch64/sve/cond_fma.c
new file mode 100644
index 000000000000..e4bc381a193d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/cond_fma.c
@@ -0,0 +1,37 @@
+/* { dg-do run { target aarch64_sve_hw } } */
+/* { dg-options "-O2 -ftree-vectorize" } */
+
+float a[256], b[256], c[256], d[256], r[256];
+
+__attribute__((noipa)) void
+f (int n)
+{
+  for (int i = 0; i < n; i++)
+    {
+      float t = d[i] > 0.f ? __builtin_fmaf (a[i], b[i], c[i]) : d[i];
+      r[i] = -t;
+    }
+}
+
+int
+main (void)
+{
+  for (int i = 0; i < 256; i++)
+    {
+      a[i] = 2.f;
+      b[i] = 3.f;
+      c[i] = 5.f;
+      d[i] = i & 1 ? 4.f : -7.f;
+      r[i] = 0.f;
+    }
+
+  f (256);
+  for (int i = 0; i < 256; i++)
+    {
+      float expected = d[i] > 0.f ? -11.f : 7.f;
+      if (r[i] != expected)
+	__builtin_abort ();
+    }
+
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/cond_fma_neg_addend.c b/gcc/testsuite/gcc.target/aarch64/sve/cond_fma_neg_addend.c
new file mode 100644
index 000000000000..e2c9dd1a6806
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/cond_fma_neg_addend.c
@@ -0,0 +1,34 @@
+/* { dg-do run { target aarch64_sve_hw } } */
+/* { dg-options "-O2 -ftree-vectorize" } */
+
+float a[256], b[256], c[256], d[256], r[256];
+
+__attribute__((noipa)) void
+f (int n)
+{
+  for (int i = 0; i < n; i++)
+    r[i] = d[i] > 0.f ? __builtin_fmaf (a[i], b[i], -c[i]) : d[i];
+}
+
+int
+main (void)
+{
+  for (int i = 0; i < 256; i++)
+    {
+      a[i] = 2.f;
+      b[i] = 3.f;
+      c[i] = 5.f;
+      d[i] = i & 1 ? 4.f : -7.f;
+      r[i] = 0.f;
+    }
+
+  f (256);
+  for (int i = 0; i < 256; i++)
+    {
+      float expected = d[i] > 0.f ? 1.f : -7.f;
+      if (r[i] != expected)
+	__builtin_abort ();
+    }
+
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/cond_fms.c b/gcc/testsuite/gcc.target/aarch64/sve/cond_fms.c
new file mode 100644
index 000000000000..e383d8eba025
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/cond_fms.c
@@ -0,0 +1,37 @@
+/* { dg-do run { target aarch64_sve_hw } } */
+/* { dg-options "-O2 -ftree-vectorize" } */
+
+float a[256], b[256], c[256], d[256], r[256];
+
+__attribute__((noipa)) void
+f (int n)
+{
+  for (int i = 0; i < n; i++)
+    {
+      float t = d[i] > 0.f ? __builtin_fmaf (a[i], b[i], -c[i]) : d[i];
+      r[i] = -t;
+    }
+}
+
+int
+main (void)
+{
+  for (int i = 0; i < 256; i++)
+    {
+      a[i] = 2.f;
+      b[i] = 3.f;
+      c[i] = 5.f;
+      d[i] = i & 1 ? 4.f : -7.f;
+      r[i] = 0.f;
+    }
+
+  f (256);
+  for (int i = 0; i < 256; i++)
+    {
+      float expected = d[i] > 0.f ? -1.f : 7.f;
+      if (r[i] != expected)
+	__builtin_abort ();
+    }
+
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/cond_fnma.c b/gcc/testsuite/gcc.target/aarch64/sve/cond_fnma.c
new file mode 100644
index 000000000000..dcee73c0c2e3
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/cond_fnma.c
@@ -0,0 +1,37 @@
+/* { dg-do run { target aarch64_sve_hw } } */
+/* { dg-options "-O2 -ftree-vectorize" } */
+
+float a[256], b[256], c[256], d[256], r[256];
+
+__attribute__((noipa)) void
+f (int n)
+{
+  for (int i = 0; i < n; i++)
+    {
+      float t = d[i] > 0.f ? __builtin_fmaf (-a[i], b[i], c[i]) : d[i];
+      r[i] = -t;
+    }
+}
+
+int
+main (void)
+{
+  for (int i = 0; i < 256; i++)
+    {
+      a[i] = 2.f;
+      b[i] = 3.f;
+      c[i] = 5.f;
+      d[i] = i & 1 ? 4.f : -7.f;
+      r[i] = 0.f;
+    }
+
+  f (256);
+  for (int i = 0; i < 256; i++)
+    {
+      float expected = d[i] > 0.f ? 1.f : 7.f;
+      if (r[i] != expected)
+	__builtin_abort ();
+    }
+
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/cond_fnms.c b/gcc/testsuite/gcc.target/aarch64/sve/cond_fnms.c
new file mode 100644
index 000000000000..c2951bc5aae8
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/cond_fnms.c
@@ -0,0 +1,37 @@
+/* { dg-do run { target aarch64_sve_hw } } */
+/* { dg-options "-O2 -ftree-vectorize" } */
+
+float a[256], b[256], c[256], d[256], r[256];
+
+__attribute__((noipa)) void
+f (int n)
+{
+  for (int i = 0; i < n; i++)
+    {
+      float t = d[i] > 0.f ? __builtin_fmaf (-a[i], b[i], -c[i]) : d[i];
+      r[i] = -t;
+    }
+}
+
+int
+main (void)
+{
+  for (int i = 0; i < 256; i++)
+    {
+      a[i] = 2.f;
+      b[i] = 3.f;
+      c[i] = 5.f;
+      d[i] = i & 1 ? 4.f : -7.f;
+      r[i] = 0.f;
+    }
+
+  f (256);
+  for (int i = 0; i < 256; i++)
+    {
+      float expected = d[i] > 0.f ? 11.f : 7.f;
+      if (r[i] != expected)
+	__builtin_abort ();
+    }
+
+  return 0;
+}