[committed] Tweak issue rate for 74K processors

[Richard Sandiford]

I'm applying this patch on behalf of David.  It tweaks the issue
rate for 74K processors for the reasons described in the comment.

Tested on mipsisa32r2-elfoabi.  Applied to trunk.

Richard


gcc/
2007-07-03  David Ung  <davidu@mips.com>

	* config/mips/mips.c (mips_issue_rate): Return 4 for 74K processors.

Index: gcc/config/mips/mips.c
===================================================================
--- gcc/config/mips/mips.c	2007-07-02 11:52:26.000000000 -0700
+++ gcc/config/mips/mips.c	2007-07-02 11:54:23.000000000 -0700
@@ -10822,6 +10822,12 @@ mips_issue_rate (void)
     case PROCESSOR_74KF2_1:
     case PROCESSOR_74KF1_1:
     case PROCESSOR_74KF3_2:
+      /* The 74k is not strictly quad-issue cpu, but can be seen as one
+	 by the scheduler.  It can issue 1 ALU, 1 AGEN and 2 FPU insns,
+	 but in reality only a maximum of 3 insns can be issued as the
+	 floating point load/stores also require a slot in the AGEN pipe.  */
+     return 4;
+
     case PROCESSOR_R4130:
     case PROCESSOR_R5400:
     case PROCESSOR_R5500: