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Remove use of ppc string instructions

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This commit is contained in:
Anthony Green
2011-11-12 15:52:08 -05:00
parent 236c939132
commit af18df2bc2
5 changed files with 225 additions and 56 deletions
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171
patches/powerpc-sysv-without-string-ops Normal file
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@@ -0,0 +1,171 @@
Index: libffi/ChangeLog
===================================================================
--- libffi.orig/ChangeLog
+++ libffi/ChangeLog
@@ -1,3 +1,9 @@
+2011-11-12 Kyle Moffett <Kyle.D.Moffett@boeing.com>
+ Anthony Green <green@moxielogic.com>
+
+ * src/ppc/sysv.S, src/ppc/ffi.c: Remove use of ppc string
+ instructions (not available on some cores, like the PPC440).
+
2011-11-12 Kimura Wataru <kimuraw@i.nifty.jp>
* m4/ax_enable_builddir: Change from string comparison to numeric
Index: libffi/src/powerpc/ffi.c
===================================================================
--- libffi.orig/src/powerpc/ffi.c
+++ libffi/src/powerpc/ffi.c
@@ -1,5 +1,6 @@
/* -----------------------------------------------------------------------
ffi.c - Copyright (C) 2011 Anthony Green
+ Copyright (C) 2011 Kyle Moffett
Copyright (C) 2008 Red Hat, Inc
Copyright (C) 2007, 2008 Free Software Foundation, Inc
Copyright (c) 1998 Geoffrey Keating
@@ -44,11 +45,6 @@ enum {
FLAG_RETURNS_64BITS = 1 << (31-28),
FLAG_RETURNS_128BITS = 1 << (31-27), /* cr6 */
- FLAG_SYSV_SMST_R4 = 1 << (31-26), /* use r4 for FFI_SYSV 8 byte
- structs. */
- FLAG_SYSV_SMST_R3 = 1 << (31-25), /* use r3 for FFI_SYSV 4 byte
- structs. */
- /* Bits (31-24) through (31-19) store shift value for SMST */
FLAG_ARG_NEEDS_COPY = 1 << (31- 7),
FLAG_FP_ARGUMENTS = 1 << (31- 6), /* cr1.eq; specified by ABI */
@@ -672,34 +668,19 @@ ffi_prep_cif_machdep (ffi_cif *cif)
break;
case FFI_TYPE_STRUCT:
- if (cif->abi == FFI_SYSV)
- {
- /* The final SYSV ABI says that structures smaller or equal 8 bytes
- are returned in r3/r4. The FFI_GCC_SYSV ABI instead returns them
- in memory. */
-
- /* Treat structs with size <= 8 bytes. */
- if (size <= 8)
- {
- flags |= FLAG_RETURNS_SMST;
- /* These structs are returned in r3. We pack the type and the
- precalculated shift value (needed in the sysv.S) into flags.
- The same applies for the structs returned in r3/r4. */
- if (size <= 4)
- {
- flags |= FLAG_SYSV_SMST_R3;
- flags |= 8 * (4 - size) << 8;
- break;
- }
- /* These structs are returned in r3 and r4. See above. */
- if (size <= 8)
- {
- flags |= FLAG_SYSV_SMST_R3 | FLAG_SYSV_SMST_R4;
- flags |= 8 * (8 - size) << 8;
- break;
- }
- }
- }
+ /*
+ * The final SYSV ABI says that structures smaller or equal 8 bytes
+ * are returned in r3/r4. The FFI_GCC_SYSV ABI instead returns them
+ * in memory.
+ *
+ * NOTE: The assembly code can safely assume that it just needs to
+ * store both r3 and r4 into a 8-byte word-aligned buffer, as
+ * we allocate a temporary buffer in ffi_call() if this flag is
+ * set.
+ */
+ if (cif->abi == FFI_SYSV && size <= 8)
+ flags |= FLAG_RETURNS_SMST;
+
#if FFI_TYPE_LONGDOUBLE != FFI_TYPE_DOUBLE
byref:
#endif
@@ -887,21 +868,32 @@ extern void FFI_HIDDEN ffi_call_LINUX64(
void
ffi_call(ffi_cif *cif, void (*fn)(void), void *rvalue, void **avalue)
{
+ /*
+ * The final SYSV ABI says that structures smaller or equal 8 bytes
+ * are returned in r3/r4. The FFI_GCC_SYSV ABI instead returns them
+ * in memory.
+ *
+ * Just to keep things simple for the assembly code, we will always
+ * bounce-buffer struct return values less than or equal to 8 bytes.
+ * This allows the ASM to handle SYSV small structures by directly
+ * writing r3 and r4 to memory without worrying about struct size.
+ */
+ unsigned int smst_buffer[2];
extended_cif ecif;
+ unsigned int rsize;
ecif.cif = cif;
ecif.avalue = avalue;
- /* If the return value is a struct and we don't have a return */
- /* value address then we need to make one */
-
- if ((rvalue == NULL) && (cif->rtype->type == FFI_TYPE_STRUCT))
- {
- ecif.rvalue = alloca(cif->rtype->size);
- }
- else
- ecif.rvalue = rvalue;
-
+ /* Ensure that we have a valid struct return value */
+ ecif.rvalue = rvalue;
+ if (cif->rtype->type == FFI_TYPE_STRUCT) {
+ rsize = cif->rtype->size;
+ if (rsize <= 8)
+ ecif.rvalue = smst_buffer;
+ else if (!rvalue)
+ ecif.rvalue = alloca(rsize);
+ }
switch (cif->abi)
{
@@ -921,6 +913,10 @@ ffi_call(ffi_cif *cif, void (*fn)(void),
FFI_ASSERT (0);
break;
}
+
+ /* Check for a bounce-buffered return value */
+ if (rvalue && ecif.rvalue == smst_buffer)
+ memcpy(rvalue, smst_buffer, rsize);
}
Index: libffi/src/powerpc/sysv.S
===================================================================
--- libffi.orig/src/powerpc/sysv.S
+++ libffi/src/powerpc/sysv.S
@@ -136,19 +136,14 @@ L(float_return_value):
b L(done_return_value)
L(small_struct_return_value):
- extrwi %r6,%r31,2,19 /* number of bytes padding = shift/8 */
- mtcrf 0x02,%r31 /* copy flags to cr[24:27] (cr6) */
- extrwi %r5,%r31,5,19 /* r5 <- number of bits of padding */
- subfic %r6,%r6,4 /* r6 <- number of useful bytes in r3 */
- bf- 25,L(done_return_value) /* struct in r3 ? if not, done. */
-/* smst_one_register: */
- slw %r3,%r3,%r5 /* Left-justify value in r3 */
- mtxer %r6 /* move byte count to XER ... */
- stswx %r3,0,%r30 /* ... and store that many bytes */
- bf+ 26,L(done_return_value) /* struct in r3:r4 ? */
- add %r6,%r6,%r30 /* adjust pointer */
- stswi %r4,%r6,4 /* store last four bytes */
- b L(done_return_value)
+ /*
+ * The C code always allocates a properly-aligned 8-byte bounce
+ * buffer to make this assembly code very simple. Just write out
+ * r3 and r4 to the buffer to allow the C code to handle the rest.
+ */
+ stw %r3, 0(%r30)
+ stw %r4, 4(%r30)
+ b L(done_return_value)
.LFE1:
END(ffi_call_SYSV)

1
patches/series
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@@ -28,6 +28,7 @@ darwin-EH-fix
more-openbsd
more-openbsd-mips
darwin11
powerpc-sysv-without-string-ops
minix
interix-patch