mangler and runtime updates for gcc 4 on ia64

Gcc 4 is doing more clever optimizations than earlier gccs. 
These changes let ghc compile and run on ia64 with gcc 4.0.3.

Register stack frames are enlarged so that all functions use the 
same size stack frame.
The code to mangle tail calls has been cleaned up and made more 
general.
Additional floating-point and special-purpose registers used by 
GCC are saved upon entering the STG runtime.
More general handling of NOP instructions.
Handling of functions with multiple epilogues or no epilogue.

1 files changed, 31 insertions, 12 deletions

diff --git a/rts/StgCRun.c b/rts/StgCRun.c
index 51388510c6..16158bdeb7 100644
--- a/rts/StgCRun.c
+++ b/rts/StgCRun.c
@@ -851,6 +851,10 @@ StgRunIsImplementedInAssembler(void)
            loc29: saved ar.pfs
            loc30: saved b0
            loc31: saved gp (gcc 3.3 uses this slot)
+           loc32: saved ar.lc
+           loc33: saved pr
+       f2  -  f5: preserved floating-point registers
+       f16 - f21: preserved floating-point registers
    -------------------------------------------------------------------------- */
 
 #ifdef ia64_HOST_ARCH
@@ -859,12 +863,13 @@ StgRunIsImplementedInAssembler(void)
 #undef RESERVED_C_STACK_BYTES
 #define RESERVED_C_STACK_BYTES 1024
 
-#if ((__GNUC__ == 3) && (__GNUC_MINOR__ >= 3)) || (__GNUC__ > 3)
-/* gcc 3.3+: leave an extra slot for gp saves */
-#define LOCALS 32
-#else
-#define LOCALS 31
-#endif
+/* We don't spill all the callee-save FP registers, only the ones that
+ * gcc has been observed to use */
+#define PRESERVED_FP_REGISTERS 10
+
+/* We always allocate 34 local and 8 output registers.  As long as gcc used
+ * fewer than 32 locals, the mangler will adjust the stack frame accordingly. */
+#define LOCALS 34
 
 static void GNUC3_ATTRIBUTE(used)
 StgRunIsImplementedInAssembler(void)
@@ -876,8 +881,8 @@ StgRunIsImplementedInAssembler(void)
 		"\tld8 r18 = [r32],8\n"			/* get procedure address */
 		"\tadds sp = -%0, sp ;;\n"		/* setup stack */
 		"\tld8 gp = [r32]\n"			/* get procedure GP */
-		"\tadds r16 = %0-(6*16), sp\n"
-		"\tadds r17 = %0-(5*16), sp ;;\n"
+		"\tadds r16 = %0-(%2*16), sp\n"
+		"\tadds r17 = %0-((%2-1)*16), sp ;;\n"
 		"\tstf.spill [r16] = f16,32\n"		/* spill callee-saved fp regs */
 		"\tstf.spill [r17] = f17,32\n"
 		"\tmov b6 = r18 ;;\n"			/* set target address */
@@ -886,12 +891,18 @@ StgRunIsImplementedInAssembler(void)
 		"\tmov loc30 = b0 ;;\n"			/* save return address */
 		"\tstf.spill [r16] = f20,32\n"
 		"\tstf.spill [r17] = f21,32\n"
+                "\tmov loc32 = ar.lc ;;\n"		/* save loop counter */
+		"\tstf.spill [r16] = f2,32\n"
+		"\tstf.spill [r17] = f3,32\n"
+                "\tmov loc33 = pr ;;\n"			/* save predicate registers */
+		"\tstf.spill [r16] = f4,32\n"
+		"\tstf.spill [r17] = f5,32\n"
 		"\tbr.few b6 ;;\n"			/* branch to function */
 		".global StgReturn\n"
 		"StgReturn:\n"
 		"\tmov r8 = loc16\n"		/* return value in r8 */
-		"\tadds r16 = %0-(6*16), sp\n"
-	    	"\tadds r17 = %0-(5*16), sp ;;\n"
+		"\tadds r16 = %0-(%2*16), sp\n"
+	    	"\tadds r17 = %0-((%2-1)*16), sp ;;\n"
 		"\tldf.fill f16 = [r16],32\n"	/* start restoring fp regs */
 		"\tldf.fill f17 = [r17],32\n"
 		"\tmov ar.pfs = loc29 ;;\n"	/* restore register frame */
@@ -900,9 +911,17 @@ StgRunIsImplementedInAssembler(void)
 		"\tmov b0 = loc30 ;;\n"		/* restore return address */
 		"\tldf.fill f20 = [r16],32\n"
 		"\tldf.fill f21 = [r17],32\n"
-		"\tadds sp = %0, sp\n"		/* restore stack */
+                "\tmov ar.lc = loc32 ;;\n"	/* restore loop counter */
+		"\tldf.fill f2 = [r16],32\n"
+		"\tldf.fill f3 = [r17],32\n"
+		"\tmov pr = loc33\n"		/* restore predicate registers */
+		"\tadds sp = %0, sp ;;\n"	/* restore stack */
+		"\tldf.fill f4 = [r16],32\n"
+		"\tldf.fill f5 = [r17],32\n"
 		"\tbr.ret.sptk.many b0 ;;\n"	/* return */
-	: : "i"(RESERVED_C_STACK_BYTES + 6*16), "i"(LOCALS));
+	: : "i"(RESERVED_C_STACK_BYTES + PRESERVED_FP_REGISTERS*16),
+            "i"(LOCALS),
+            "i"(PRESERVED_FP_REGISTERS));
 }
 
 #endif