inhibit the sincos optimization when the target has sin and cos instructions

[Cesar Philippidis <cesar@codesourcery.com>]

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The cse_sincos pass tries to optimize sequences such as

  sin (x);
  cos (x);

into a single call to sincos, or cexpi, when available. However, the
nvptx target has sin and cos instructions, albeit with some loss of
precision (so it's only enabled with -ffast-math). This patch teaches
cse_sincos pass to ignore sin, cos and cexpi instructions when the
target can expand those calls. This yields a 6x speedup in 314.omriq
from spec accel when running on Nvidia accelerators.

Is this OK for trunk?

Cesar

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2016-05-13  Cesar Philippidis  <cesar@codesourcery.com>

	gcc/
	* tree-ssa-math-opts.c (pass_cse_sincos::execute): Don't optimize
	sin and cos calls when the target has instructions for them.
	
	gcc/testsuite/
	* gcc.target/nvptx/sincos.c: New test.


diff --git a/gcc/testsuite/gcc.target/nvptx/sincos.c b/gcc/testsuite/gcc.target/nvptx/sincos.c
new file mode 100644
index 0000000..921ec41
--- /dev/null
+++ b/gcc/testsuite/gcc.target/nvptx/sincos.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -ffast-math" } */
+
+extern float sinf (float);
+extern float cosf (float);
+
+float
+sincos_add (float x)
+{
+  float s = sinf (x);
+  float c = cosf (x);
+
+  return s + c;
+}
+
+/* { dg-final { scan-assembler-times "sin.approx.f32" 1 } } */
+/* { dg-final { scan-assembler-times "cos.approx.f32" 1 } } */
diff --git a/gcc/tree-ssa-math-opts.c b/gcc/tree-ssa-math-opts.c
index 81688cd..38051e1 100644
--- a/gcc/tree-ssa-math-opts.c
+++ b/gcc/tree-ssa-math-opts.c
@@ -1806,6 +1806,11 @@ pass_cse_sincos::execute (function *fun)
 		CASE_CFN_COS:
 		CASE_CFN_SIN:
 		CASE_CFN_CEXPI:
+		  /* Don't modify these calls if they can be translated
+		     directly into hardware instructions.  */
+		  if (replacement_internal_fn (as_a <gcall *> (stmt))
+		      != IFN_LAST)
+		    break;
 		  /* Make sure we have either sincos or cexp.  */
 		  if (!targetm.libc_has_function (function_c99_math_complex)
 		      && !targetm.libc_has_function (function_sincos))