libgo: break dependence on libgcc unwind-pe.h
The C portion of the Go runtime includes the header "unwind-pe.h" from
libgcc, which contains some constants and a few small routines for
decoding pointer values within unwind info. This patch gets rid of
that include and instead adds a re-implementation of that
functionality in the single file that uses it. The intent is to allow
the C runtime portion of libgo to be built without a companion GCC
installation.
Reviewed-on: https://go-review.googlesource.com/90235
From-SVN: r259861
This commit is contained in:
Ian Lance Taylor
parent
27db01d803
commit
019808c95c
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@ -10,11 +10,30 @@
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#include <unistd.h>
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#include "unwind.h"
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#define NO_SIZE_OF_ENCODED_VALUE
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#include "unwind-pe.h"
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#include "runtime.h"
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/* These constants are documented here:
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https://refspecs.linuxfoundation.org/LSB_3.0.0/LSB-PDA/LSB-PDA/dwarfext.html
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*/
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#define DW_EH_PE_omit 0xff
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#define DW_EH_PE_absptr 0x00
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#define DW_EH_PE_uleb128 0x01
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#define DW_EH_PE_udata2 0x02
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#define DW_EH_PE_udata4 0x03
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#define DW_EH_PE_udata8 0x04
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#define DW_EH_PE_sleb128 0x09
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#define DW_EH_PE_sdata2 0x0A
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#define DW_EH_PE_sdata4 0x0B
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#define DW_EH_PE_sdata8 0x0C
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#define DW_EH_PE_pcrel 0x10
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#define DW_EH_PE_textrel 0x20
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#define DW_EH_PE_datarel 0x30
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#define DW_EH_PE_funcrel 0x40
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#define DW_EH_PE_aligned 0x50
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#define DW_EH_PE_indirect 0x80
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/* The code for a Go exception. */
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#ifdef __ARM_EABI_UNWINDER__
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@ -109,6 +128,150 @@ throwException ()
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abort ();
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}
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static inline _Unwind_Ptr
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encoded_value_base (uint8_t encoding, struct _Unwind_Context *context)
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{
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if (encoding == DW_EH_PE_omit)
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return 0;
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switch (encoding & 0x70)
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{
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case DW_EH_PE_absptr:
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case DW_EH_PE_pcrel:
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case DW_EH_PE_aligned:
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return 0;
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case DW_EH_PE_textrel:
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return _Unwind_GetTextRelBase(context);
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case DW_EH_PE_datarel:
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return _Unwind_GetDataRelBase(context);
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case DW_EH_PE_funcrel:
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return _Unwind_GetRegionStart(context);
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}
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abort ();
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}
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/* Read an unsigned leb128 value. */
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static inline const uint8_t *
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read_uleb128 (const uint8_t *p, _uleb128_t *val)
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{
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unsigned int shift = 0;
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_uleb128_t result = 0;
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uint8_t byte;
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do
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{
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byte = *p++;
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result |= ((_uleb128_t)byte & 0x7f) << shift;
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shift += 7;
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}
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while (byte & 0x80);
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*val = result;
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return p;
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}
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/* Similar, but read a signed leb128 value. */
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static inline const uint8_t *
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read_sleb128 (const uint8_t *p, _sleb128_t *val)
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{
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unsigned int shift = 0;
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_uleb128_t result = 0;
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uint8_t byte;
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do
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{
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byte = *p++;
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result |= ((_uleb128_t)byte & 0x7f) << shift;
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shift += 7;
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}
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while (byte & 0x80);
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/* sign extension */
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if (shift < (8 * sizeof(result)) && (byte & 0x40) != 0)
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result |= (((_uleb128_t)~0) << shift);
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*val = (_sleb128_t)result;
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return p;
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}
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#define ROUND_UP_TO_PVB(x) (x + sizeof(void *) - 1) &- sizeof(void *)
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#define COPY_AND_ADVANCE(dst, ptr, typ) \
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(dst = *((const typ*)ptr), \
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ptr += sizeof(typ))
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static inline const uint8_t *
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read_encoded_value (struct _Unwind_Context *context, uint8_t encoding,
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const uint8_t *p, _Unwind_Ptr *val)
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{
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_Unwind_Ptr base = encoded_value_base (encoding, context);
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_Unwind_Internal_Ptr decoded = 0;
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const uint8_t *origp = p;
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if (encoding == DW_EH_PE_aligned)
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{
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_Unwind_Internal_Ptr uip = (_Unwind_Internal_Ptr)p;
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uip = ROUND_UP_TO_PVB (uip);
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decoded = *(_Unwind_Internal_Ptr *)uip;
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p = (const uint8_t *)(uip + sizeof(void *));
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}
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else
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{
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switch (encoding & 0x0f)
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{
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case DW_EH_PE_sdata2:
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case DW_EH_PE_udata2:
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COPY_AND_ADVANCE (decoded, p, uint16_t);
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break;
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case DW_EH_PE_sdata4:
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case DW_EH_PE_udata4:
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COPY_AND_ADVANCE (decoded, p, uint32_t);
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break;
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case DW_EH_PE_sdata8:
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case DW_EH_PE_udata8:
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COPY_AND_ADVANCE (decoded, p, uint64_t);
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break;
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case DW_EH_PE_uleb128:
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{
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_uleb128_t value;
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p = read_uleb128 (p, &value);
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decoded = (_Unwind_Internal_Ptr)value;
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break;
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}
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case DW_EH_PE_sleb128:
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{
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_sleb128_t value;
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p = read_sleb128 (p, &value);
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decoded = (_Unwind_Internal_Ptr)value;
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break;
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}
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case DW_EH_PE_absptr:
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decoded = (_Unwind_Internal_Ptr)(*(const void *const *)p);
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p += sizeof(void *);
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break;
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default:
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abort ();
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}
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if (decoded == 0)
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{
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*val = decoded;
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return p;
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}
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if ((encoding & 0x70) == DW_EH_PE_pcrel)
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decoded += ((_Unwind_Internal_Ptr)origp);
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else
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decoded += base;
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if ((encoding & DW_EH_PE_indirect) != 0)
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decoded = *(_Unwind_Internal_Ptr *)decoded;
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}
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*val = decoded;
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return p;
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}
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/* The rest of this code is really similar to gcc/unwind-c.c and
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libjava/exception.cc. */
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