[gcc r15-1817] [PATCH] match.pd: Fold x/sqrt(x) to sqrt(x)

[Kyrylo Tkachov via Gcc-cvs]

https://gcc.gnu.org/g:8dc5ad3ce8d4d2cd6cc2b7516d282395502fdf7d

commit r15-1817-g8dc5ad3ce8d4d2cd6cc2b7516d282395502fdf7d
Author: Jennifer Schmitz <jschm...@nvidia.com>
Date:   Wed Jul 3 14:40:42 2024 +0200

    [PATCH] match.pd: Fold x/sqrt(x) to sqrt(x)
    
    This patch adds a pattern in match.pd folding x/sqrt(x) to sqrt(x) for 
-funsafe-math-optimizations. Test cases were added for double, float, and long 
double.
    
    The patch was bootstrapped and regtested on aarch64-linux-gnu, no 
regression.
    Ok for mainline?
    
    Signed-off-by: Jennifer Schmitz <jschm...@nvidia.com>
    
    gcc/
    
            * match.pd: Fold x/sqrt(x) to sqrt(x).
    
    gcc/testsuite/
    
            * gcc.dg/tree-ssa/sqrt_div.c: New test.

Diff:
---
 gcc/match.pd                             |  4 ++++
 gcc/testsuite/gcc.dg/tree-ssa/sqrt_div.c | 23 +++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/gcc/match.pd b/gcc/match.pd
index 7fff7b5f9fe..a2e205b3207 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -7770,6 +7770,10 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
      when the operand has that value.)  */
 
 (if (flag_unsafe_math_optimizations)
+ /* Simplify x / sqrt(x) -> sqrt(x).  */
+ (simplify
+  (rdiv @0 (SQRT @0)) (SQRT @0))
+
  /* Simplify sqrt(x) * sqrt(x) -> x.  */
  (simplify
   (mult (SQRT_ALL@1 @0) @1)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/sqrt_div.c 
b/gcc/testsuite/gcc.dg/tree-ssa/sqrt_div.c
new file mode 100644
index 00000000000..2ae481b7982
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/sqrt_div.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -ffast-math -fdump-tree-forwprop-details" } */
+/* { dg-require-effective-target c99_runtime } */
+
+#define T(n, type, fname)          \
+type f##n (type x)                 \
+{                                  \
+  type t1 = __builtin_##fname (x); \
+  type t2 = x / t1;                \
+  return t2;                       \
+}                               
+
+T(1, double, sqrt)
+
+/* { dg-final { scan-tree-dump "gimple_simplified to t2_\[0-9\]+ = 
__builtin_sqrt .x_\[0-9\]*.D.." "forwprop1" } }     */
+
+T(2, float, sqrtf )
+
+/* { dg-final { scan-tree-dump "gimple_simplified to t2_\[0-9\]+ = 
__builtin_sqrtf .x_\[0-9\]*.D.." "forwprop1" } }     */
+
+T(3, long double, sqrtl)
+
+/* { dg-final { scan-tree-dump "gimple_simplified to t2_\[0-9\]+ = 
__builtin_sqrtl .x_\[0-9\]*.D.." "forwprop1" } } */