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[4/17] Implement TARGET_C_EXCESS_PRECISION for m68k

Message ID 1478878647-22547-5-git-send-email-james.greenhalgh@arm.com
State New
Headers show

Commit Message

James Greenhalgh Nov. 11, 2016, 3:37 p.m. UTC 
---
This patch was approved in the original form, and the delta to here would
apply under the obvious rule:
  https://gcc.gnu.org/ml/gcc-patches/2016-09/msg02414.html
---

On Fri, Sep 30, 2016 at 11:28:28AM -0600, Jeff Law wrote:
> On 09/30/2016 11:01 AM, James Greenhalgh wrote:

> >

> >Hi,

> >

> >This patch ports the logic from m68k's TARGET_FLT_EVAL_METHOD to the new

> >target hook TARGET_C_EXCESS_PRECISION.

> >

> >Patch tested by building an m68k-none-elf toolchain and running

> >m68k.exp (without the ability to execute) with no regressions, and manually

> >inspecting the output assembly code when compiling

> >testsuite/gcc.target/i386/excess-precision* to show no difference in

> >code-generation.

> >

> >OK?

> >

> >Thanks,

> >James

> >

> >---

> >gcc/

> >

> >2016-09-30  James Greenhalgh  <james.greenhalgh@arm.com>

> >

> >	* config/m68k/m68k.c (m68k_excess_precision): New.

> >	(TARGET_C_EXCESS_PRECISION): Define.

> OK when prereqs are approved.  Similarly for other targets where you

> needed to add this hook.


Thanks Jeff, Andreas,

I spotted a very silly bug when I was retesting this patch set - when I
swapped the namespace for the new traget macro it changed from
TARGET_EXCESS_PRECISION to TARGET_C_EXCESS_PRECISION but I failed to
update the m68k patch to reflect that.

This second revision fixes that (obvious) oversight.

Thanks,
James

---
gcc/

2016-11-09  James Greenhalgh  <james.greenhalgh@arm.com>

	* config/m68k/m68k.c (m68k_excess_precision): New.
	(TARGET_C_EXCESS_PRECISION): Define.
diff mbox

Patch

diff --git a/gcc/config/m68k/m68k.c b/gcc/config/m68k/m68k.c
index ce56692..22165d6 100644
--- a/gcc/config/m68k/m68k.c
+++ b/gcc/config/m68k/m68k.c
@@ -183,6 +183,8 @@  static rtx m68k_function_arg (cumulative_args_t, machine_mode,
 static bool m68k_cannot_force_const_mem (machine_mode mode, rtx x);
 static bool m68k_output_addr_const_extra (FILE *, rtx);
 static void m68k_init_sync_libfuncs (void) ATTRIBUTE_UNUSED;
+static enum flt_eval_method
+m68k_excess_precision (enum excess_precision_type);
 
 /* Initialize the GCC target structure.  */
 
@@ -323,6 +325,9 @@  static void m68k_init_sync_libfuncs (void) ATTRIBUTE_UNUSED;
 #undef TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA
 #define TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA m68k_output_addr_const_extra
 
+#undef TARGET_C_EXCESS_PRECISION
+#define TARGET_C_EXCESS_PRECISION m68k_excess_precision
+
 /* The value stored by TAS.  */
 #undef TARGET_ATOMIC_TEST_AND_SET_TRUEVAL
 #define TARGET_ATOMIC_TEST_AND_SET_TRUEVAL 128
@@ -6532,4 +6537,36 @@  m68k_epilogue_uses (int regno ATTRIBUTE_UNUSED)
 	      == m68k_fk_interrupt_handler));
 }
 
+
+/* Implement TARGET_C_EXCESS_PRECISION.
+
+   Set the value of FLT_EVAL_METHOD in float.h.  When using 68040 fp
+   instructions, we get proper intermediate rounding, otherwise we
+   get extended precision results.  */
+
+static enum flt_eval_method
+m68k_excess_precision (enum excess_precision_type type)
+{
+  switch (type)
+    {
+      case EXCESS_PRECISION_TYPE_FAST:
+	/* The fastest type to promote to will always be the native type,
+	   whether that occurs with implicit excess precision or
+	   otherwise.  */
+	return FLT_EVAL_METHOD_PROMOTE_TO_FLOAT;
+      case EXCESS_PRECISION_TYPE_STANDARD:
+      case EXCESS_PRECISION_TYPE_IMPLICIT:
+	/* Otherwise, the excess precision we want when we are
+	   in a standards compliant mode, and the implicit precision we
+	   provide can be identical.  */
+	if (TARGET_68040 || ! TARGET_68881)
+	  return FLT_EVAL_METHOD_PROMOTE_TO_FLOAT;
+
+	return FLT_EVAL_METHOD_PROMOTE_TO_LONG_DOUBLE;
+      default:
+	gcc_unreachable ();
+    }
+  return FLT_EVAL_METHOD_UNPREDICTABLE;
+}
+
 #include "gt-m68k.h"