mips.c (mips_conditional_register_usage): Do not use t[0-7] registers in MIPS16…

mips.c (mips_conditional_register_usage): Do not use t[0-7] registers in MIPS16 mode when optimizing for size.

2013-07-11  Steve Ellcey  <sellcey@mips.com>

	* config/mips/mips.c (mips_conditional_register_usage): Do not
	use t[0-7] registers in MIPS16 mode when optimizing for size.

From-SVN: r200914

gcc/ChangeLog

+2013-07-11  Steve Ellcey  <sellcey@mips.com>
+
+	* config/mips/mips.c (mips_conditional_register_usage): Do not
+	use t[0-7] registers in MIPS16 mode when optimizing for size.
+
 2013-07-11  Sriraman Tallam  <tmsriram@google.com>
 
 	* config/i386/i386.c (dispatch_function_versions): Fix array

gcc/config/mips/mips.c

@@ -17199,10 +17199,17 @@ mips_conditional_register_usage (void)
     }
   if (TARGET_MIPS16)
     {
-      /* In MIPS16 mode, we permit the $t temporary registers to be used
-	 for reload.  We prohibit the unused $s registers, since they
+      /* In MIPS16 mode, we prohibit the unused $s registers, since they
 	 are call-saved, and saving them via a MIPS16 register would
-	 probably waste more time than just reloading the value.  */
+	 probably waste more time than just reloading the value.
+
+	 We permit the $t temporary registers when optimizing for speed
+	 but not when optimizing for space because using them results in
+	 code that is larger (but faster) then not using them.  We do
+	 allow $24 (t8) because it is used in CMP and CMPI instructions
+	 and $25 (t9) because it is used as the function call address in
+	 SVR4 PIC code.  */
+
       fixed_regs[18] = call_used_regs[18] = 1;
       fixed_regs[19] = call_used_regs[19] = 1;
       fixed_regs[20] = call_used_regs[20] = 1;
@@ -17212,6 +17219,17 @@ mips_conditional_register_usage (void)
       fixed_regs[26] = call_used_regs[26] = 1;
       fixed_regs[27] = call_used_regs[27] = 1;
       fixed_regs[30] = call_used_regs[30] = 1;
+      if (optimize_size)
+	{
+	  fixed_regs[8] = call_used_regs[8] = 1;
+	  fixed_regs[9] = call_used_regs[9] = 1;
+	  fixed_regs[10] = call_used_regs[10] = 1;
+	  fixed_regs[11] = call_used_regs[11] = 1;
+	  fixed_regs[12] = call_used_regs[12] = 1;
+	  fixed_regs[13] = call_used_regs[13] = 1;
+	  fixed_regs[14] = call_used_regs[14] = 1;
+	  fixed_regs[15] = call_used_regs[15] = 1;
+	}
 
       /* Do not allow HI and LO to be treated as register operands.
 	 There are no MTHI or MTLO instructions (or any real need