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.greenha...@arm.com>
* config/m68k/m68k.c (m68k_excess_precision): New.
(TARGET_C_EXCESS_PRECISION): Define.
diff --git a/gcc/config/m68k/m68k.c b/gcc/config/m68k/m68k.c
index a104193..c858d7e 100644
--- a/gcc/config/m68k/m68k.c
+++ b/gcc/config/m68k/m68k.c
@@ -182,6 +182,8 @@ 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. */
@@ -322,6 +324,9 @@ 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_EXCESS_PRECISION
+#define TARGET_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
@@ -6528,4 +6533,36 @@ m68k_epilogue_uses (int regno ATTRIBUTE_UNUSED)
== m68k_fk_interrupt_handler));
}
+
+/* Implement TARGET_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"
