[libunwind] Change unw_word_t to always have the same size as the pointer size

[mstorsjo]

Summary

This matches the original libunwind API. This also unifies the type between ARM EHABI and the other configurations, and allows getting rid of a number of casts in log messages.

The cursor size updates for ppc and or1k are untested, but unw_proc_info_t shrinks by 4 uint64_t units on 32 bit platforms.

[rnk]

Doesn't this change the ABI considerably? I suspect Apple cares about that.

Is remotely unwinding a 64-bit thread from a 32-bit process a concern? That's the main use case that forcing 64-bit words seems to enable.

[mstorsjo]

In D39365#909706, @rnk wrote:

Doesn't this change the ABI considerably? I suspect Apple cares about that.

It does change the ABI of the lower level unw_* API yes, but it shouldn't be visible outside via the higher level APIs.

Is remotely unwinding a 64-bit thread from a 32-bit process a concern? That's the main use case that forcing 64-bit words seems to enable.

If that's a concern, then the other patch I propsed earlier would make things even more consistent, by using 64 bit words even on ARM EHABI: https://reviews.llvm.org/D39280

[compnerd]

@rnk given that the remote unwinder is completely unimplemented ATM, I think that this isn't a big concern. I'm not sure that this makes anything worse, but I do feel that it is making things better (especially since RemoteAddressSpace is currently mostly just a '// FIXME: implement').

[theraven]

This makes things worse for us. On CHERI, [u]intptr_t is a (typedef for a) built-in type that can hold a capability. Having unw_word_t be uintptr_t made LLVM's libunwind considerably easier to port than the HP unwinder would have been, because uintptr_t is a type that is able to hold either any integer-register type or a pointer, whereas neither uint32_t nor uint64_t is. This will be true for any architecture that supports any kind of fat-pointer representation.

What is the motivation for this change? It appears to be changing working code in such a way that removes future proofing.

Replacing integer casts with void* casts and using PRIxPTR consistently would make life easier, though the use of PRIxPTR vs PRIXPTR seems inconsistent (as is the original use of %x vs %X.

[mstorsjo]

In D39365#910590, @theraven wrote:

This makes things worse for us. On CHERI, [u]intptr_t is a (typedef for a) built-in type that can hold a capability. Having unw_word_t be uintptr_t

For understanding, I guess you meant "Having unw_word_t be uint64_t" here? Because othewise, that's exactly the change I'm doing - currently it's uint64_t while I'm proposing making it uintptr_t - that you're saying is easier to work with?

made LLVM's libunwind considerably easier to port than the HP unwinder would have been, because uintptr_t is a type that is able to hold either any integer-register type or a pointer, whereas neither uint32_t nor uint64_t is. This will be true for any architecture that supports any kind of fat-pointer representation.

What is the motivation for this change? It appears to be changing working code in such a way that removes future proofing.

Replacing integer casts with void* casts and using PRIxPTR consistently would make life easier,

The original root cause that triggered me to write this, is that currently unw_word_t is uint32_t for ARM EHABI but uint64_t for everything else. Since I want to add support for ARM/DWARF (D39251), this required adding casts in UnwindLevel1.c which currently implicitly assumes that unw_word_t is uint64_t. Instead of adding such casts, I made one patch to change it to consistently be uint64_t (D39280) even on ARM EHABI, but that got the review comment that unw_word_t should match uintptr_t, thus I wrote this patch.

So the options currently seem to be:

• Keep the inconsistency and add ifdefs for the context size for ARM (which would be different for EHABI vs DWARF), where we already have ifdefs for the context size depending on if WMMX is enabled or not - that would make 4 different hardcoded sizes in __libunwind_config.h.
• Make unw_word_t be uint32_t on ARM, uint64_t everywhere else (minimal change from status quo), add casts of one form or another in UnwindLevel1.c (D39251)
• Make unw_word_t be uin64_t consistently everywhere (D39280)
• Make unw_word_t be uintptr_t (this one)

I don't have too much of a preference, as long as people settle on one - so far every review has pointed me in a different direction.

though the use of PRIxPTR vs PRIXPTR seems inconsistent (as is the original use of %x vs %X.

Yes, I've kept these as inconsistent as they were originally - if peferred I can make the ones I touch consistently either upper or lower case.

[theraven]

In D39365#910622, @mstorsjo wrote:

In D39365#910590, @theraven wrote:

This makes things worse for us. On CHERI, [u]intptr_t is a (typedef for a) built-in type that can hold a capability. Having unw_word_t be uintptr_t

For understanding, I guess you meant "Having unw_word_t be uint64_t" here? Because othewise, that's exactly the change I'm doing - currently it's uint64_t while I'm proposing making it uintptr_t - that you're saying is easier to work with?

Sorry - it looks as if I read the diff back to front. I seem to be less awake than I thought today...

Reading the diff the correct way around, this seems like a definite improvement.

though the use of PRIxPTR vs PRIXPTR seems inconsistent (as is the original use of %x vs %X.

Yes, I've kept these as inconsistent as they were originally - if peferred I can make the ones I touch consistently either upper or lower case.

I'd generally prefer PRIxPTR, because most of the time I either don't care or want to copy and paste for comparison with objdump output (which uses lower case).

[mstorsjo]

In D39365#910713, @theraven wrote:

Sorry - it looks as if I read the diff back to front. I seem to be less awake than I thought today...

Reading the diff the correct way around, this seems like a definite improvement.

Ok, thanks! Then it's just left to see if @rnk agrees with @compnerd 's reasoning.

though the use of PRIxPTR vs PRIXPTR seems inconsistent (as is the original use of %x vs %X.

Yes, I've kept these as inconsistent as they were originally - if peferred I can make the ones I touch consistently either upper or lower case.

I'd generally prefer PRIxPTR, because most of the time I either don't care or want to copy and paste for comparison with objdump output (which uses lower case).

Ok, I'll make it consistent in the next update or when committing.

[rnk]

In D39365#909912, @compnerd wrote:

@rnk given that the remote unwinder is completely unimplemented ATM, I think that this isn't a big concern. I'm not sure that this makes anything worse, but I do feel that it is making things better (especially since RemoteAddressSpace is currently mostly just a '// FIXME: implement').

Sounds good to me, just wanted to check. :)

include/__libunwind_config.h

#if defined(__arm__) && !defined(__USING_SJLJ_EXCEPTIONS__) && \
     !defined(__ARM_DWARF_EH__)
 #define _LIBUNWIND_ARM_EHABI
 #endif
 
 #if defined(_LIBUNWIND_IS_NATIVE_ONLY)
 # if defined(__i386__)
 #  define _LIBUNWIND_TARGET_I386
 #  define _LIBUNWIND_CONTEXT_SIZE 8
-#  define _LIBUNWIND_CURSOR_SIZE 19
+#  define _LIBUNWIND_CURSOR_SIZE 15
 #  define _LIBUNWIND_HIGHEST_DWARF_REGISTER 8
 # elif defined(__x86_64__)
 #  define _LIBUNWIND_TARGET_X86_64 1
 #  if defined(_WIN64)
 #    define _LIBUNWIND_CONTEXT_SIZE 54
 #    define _LIBUNWIND_CURSOR_SIZE 66
 #    define _LIBUNWIND_HIGHEST_DWARF_REGISTER 32
 #  else
 #    define _LIBUNWIND_CONTEXT_SIZE 21
 #    define _LIBUNWIND_CURSOR_SIZE 33
 #    define _LIBUNWIND_HIGHEST_DWARF_REGISTER 16
 #  endif
 # elif defined(__ppc__)
 #  define _LIBUNWIND_TARGET_PPC 1
 #  define _LIBUNWIND_CONTEXT_SIZE 117
-#  define _LIBUNWIND_CURSOR_SIZE 128
+#  define _LIBUNWIND_CURSOR_SIZE 124
 #  define _LIBUNWIND_HIGHEST_DWARF_REGISTER 112
 # elif defined(__aarch64__)
 #  define _LIBUNWIND_TARGET_AARCH64 1
 #  define _LIBUNWIND_CONTEXT_SIZE 66
 #  define _LIBUNWIND_CURSOR_SIZE 78
 #  define _LIBUNWIND_HIGHEST_DWARF_REGISTER 95
 # elif defined(__arm__)
 #  define _LIBUNWIND_TARGET_ARM 1
 #  if defined(__ARM_WMMX)
 #    define _LIBUNWIND_CONTEXT_SIZE 61
 #    define _LIBUNWIND_CURSOR_SIZE 68
 #  else
 #    define _LIBUNWIND_CONTEXT_SIZE 42
 #    define _LIBUNWIND_CURSOR_SIZE 49
 #  endif
 #  define _LIBUNWIND_HIGHEST_DWARF_REGISTER 95
 # elif defined(__or1k__)
 #  define _LIBUNWIND_TARGET_OR1K 1
 #  define _LIBUNWIND_CONTEXT_SIZE 16
-#  define _LIBUNWIND_CURSOR_SIZE 28
+#  define _LIBUNWIND_CURSOR_SIZE 24
 #  define _LIBUNWIND_HIGHEST_DWARF_REGISTER 31
 # else
 #  error "Unsupported architecture."
 # endif
 #else // !_LIBUNWIND_IS_NATIVE_ONLY
 # define _LIBUNWIND_TARGET_I386
 # define _LIBUNWIND_TARGET_X86_64 1
 # define _LIBUNWIND_TARGET_PPC 1

include/libunwind.h

 struct unw_cursor_t {
   uint64_t data[_LIBUNWIND_CURSOR_SIZE];
 };
 typedef struct unw_cursor_t unw_cursor_t;
 
 typedef struct unw_addr_space *unw_addr_space_t;
 
 typedef int unw_regnum_t;
+typedef uintptr_t unw_word_t;
 #if defined(_LIBUNWIND_ARM_EHABI)
-typedef uint32_t unw_word_t;
 typedef uint64_t unw_fpreg_t;
 #else
-typedef uint64_t unw_word_t;
 typedef double unw_fpreg_t;
 #endif
 
 struct unw_proc_info_t {
   unw_word_t  start_ip;         /* start address of function */
   unw_word_t  end_ip;           /* address after end of function */
   unw_word_t  lsda;             /* address of language specific data area, */
                                 /*  or zero if not used */

src/Unwind-EHABI.cpp

 //===--------------------------- Unwind-EHABI.cpp -------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //
 //  Implements ARM zero-cost C++ exceptions
 //
 //===----------------------------------------------------------------------===//
 
 #include "Unwind-EHABI.h"
 
 #if defined(_LIBUNWIND_ARM_EHABI)
 
+#include <inttypes.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include <type_traits>
 
if (_LIBUNWIND_TRACING_UNWINDING) {
       unw_word_t offset;
       if ((unw_get_proc_name(cursor, functionBuf, sizeof(functionBuf),
                              &offset) != UNW_ESUCCESS) ||
           (frameInfo.start_ip + offset > frameInfo.end_ip))
         functionName = ".anonymous.";
       unw_word_t pc;
       unw_get_reg(cursor, UNW_REG_IP, &pc);
       _LIBUNWIND_TRACE_UNWINDING(
-          "unwind_phase1(ex_ojb=%p): pc=0x%llX, start_ip=0x%llX, func=%s, "
-          "lsda=0x%llX, personality=0x%llX",
-          static_cast<void *>(exception_object), (long long)pc,
-          (long long)frameInfo.start_ip, functionName,
-          (long long)frameInfo.lsda, (long long)frameInfo.handler);
+          "unwind_phase1(ex_ojb=%p): pc=0x%" PRIXPTR ", start_ip=0x%" PRIXPTR ", func=%s, "
+          "lsda=0x%" PRIXPTR ", personality=0x%" PRIXPTR,
+          static_cast<void *>(exception_object), pc,
+          frameInfo.start_ip, functionName,
+          frameInfo.lsda, frameInfo.handler);
     }
 
     // If there is a personality routine, ask it if it will want to stop at
     // this frame.
     if (frameInfo.handler != 0) {
       __personality_routine p =
           (__personality_routine)(long)(frameInfo.handler);
       _LIBUNWIND_TRACE_UNWINDING(
if (_LIBUNWIND_TRACING_UNWINDING) {
       char functionBuf[512];
       const char *functionName = functionBuf;
       unw_word_t offset;
       if ((unw_get_proc_name(cursor, functionBuf, sizeof(functionBuf),
                              &offset) != UNW_ESUCCESS) ||
           (frameInfo.start_ip + offset > frameInfo.end_ip))
         functionName = ".anonymous.";
       _LIBUNWIND_TRACE_UNWINDING(
-          "unwind_phase2(ex_ojb=%p): start_ip=0x%llX, func=%s, sp=0x%llX, "
-          "lsda=0x%llX, personality=0x%llX",
-          static_cast<void *>(exception_object), (long long)frameInfo.start_ip,
-          functionName, (long long)sp, (long long)frameInfo.lsda,
-          (long long)frameInfo.handler);
+          "unwind_phase2(ex_ojb=%p): start_ip=0x%" PRIXPTR ", func=%s, sp=0x%" PRIXPTR ", "
+          "lsda=0x%" PRIXPTR ", personality=0x%" PRIXPTR "",
+          static_cast<void *>(exception_object), frameInfo.start_ip,
+          functionName, sp, frameInfo.lsda,
+          frameInfo.handler);
     }
 
     // If there is a personality routine, tell it we are unwinding.
     if (frameInfo.handler != 0) {
       __personality_routine p =
           (__personality_routine)(long)(frameInfo.handler);
       struct _Unwind_Context *context = (struct _Unwind_Context *)(cursor);
       // EHABI #7.2
if (frameInfo.handler != 0) {
             static_cast<void *>(exception_object));
         // Personality routine says to transfer control to landing pad.
         // We may get control back if landing pad calls _Unwind_Resume().
         if (_LIBUNWIND_TRACING_UNWINDING) {
           unw_word_t pc;
           unw_get_reg(cursor, UNW_REG_IP, &pc);
           unw_get_reg(cursor, UNW_REG_SP, &sp);
           _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): re-entering "
-                                     "user code with ip=0x%llX, sp=0x%llX",
+                                     "user code with ip=0x%" PRIXPTR ", sp=0x%" PRIXPTR,
                                      static_cast<void *>(exception_object),
-                                     (long long)pc, (long long)sp);
+                                     pc, sp);
         }
 
         {
           // EHABI #7.4.1 says we need to preserve pc for when _Unwind_Resume
           // is called back, to find this same frame.
           unw_word_t pc;
           unw_get_reg(cursor, UNW_REG_IP, &pc);
           exception_object->unwinder_cache.reserved2 = (uint32_t)pc;

src/UnwindLevel1-gcc-ext.c

#endif // defined(_LIBUNWIND_ARM_EHABI)
     // debugging
     if (_LIBUNWIND_TRACING_UNWINDING) {
       char functionName[512];
       unw_proc_info_t frame;
       unw_word_t offset;
       unw_get_proc_name(&cursor, functionName, 512, &offset);
       unw_get_proc_info(&cursor, &frame);
       _LIBUNWIND_TRACE_UNWINDING(
-          " _backtrace: start_ip=0x%llX, func=%s, lsda=0x%llX, context=%p",
-          (long long)frame.start_ip, functionName, (long long)frame.lsda,
+          " _backtrace: start_ip=0x%" PRIXPTR ", func=%s, lsda=0x%" PRIXPTR ", context=%p",
+          frame.start_ip, functionName, frame.lsda,
           (void *)&cursor);
     }
 
     // call trace function with this frame
     result = (*callback)((struct _Unwind_Context *)(&cursor), ref);
     if (result != _URC_NO_REASON) {
       _LIBUNWIND_TRACE_UNWINDING(
           " _backtrace: ended because callback returned %d", result);

 }
 
 /// Returns the CFA (call frame area, or stack pointer at start of function)
 /// for the current context.
 _LIBUNWIND_EXPORT uintptr_t _Unwind_GetCFA(struct _Unwind_Context *context) {
   unw_cursor_t *cursor = (unw_cursor_t *)context;
   unw_word_t result;
   unw_get_reg(cursor, UNW_REG_SP, &result);
-  _LIBUNWIND_TRACE_API("_Unwind_GetCFA(context=%p) => 0x%" PRIx64,
-                       (void *)context, (uint64_t)result);
+  _LIBUNWIND_TRACE_API("_Unwind_GetCFA(context=%p) => 0x%" PRIxPTR,
+                       (void *)context, result);
   return (uintptr_t)result;
 }
 
 
 /// Called by personality handler during phase 2 to get instruction pointer.
 /// ipBefore is a boolean that says if IP is already adjusted to be the call
 /// site address.  Normally IP is the return address.
 _LIBUNWIND_EXPORT uintptr_t _Unwind_GetIPInfo(struct _Unwind_Context *context,

src/UnwindLevel1.c

if (_LIBUNWIND_TRACING_UNWINDING) {
       unw_word_t offset;
       if ((unw_get_proc_name(cursor, functionBuf, sizeof(functionBuf),
                              &offset) != UNW_ESUCCESS) ||
           (frameInfo.start_ip + offset > frameInfo.end_ip))
         functionName = ".anonymous.";
       unw_word_t pc;
       unw_get_reg(cursor, UNW_REG_IP, &pc);
       _LIBUNWIND_TRACE_UNWINDING(
-          "unwind_phase1(ex_ojb=%p): pc=0x%" PRIx64 ", start_ip=0x%" PRIx64
-          ", func=%s, lsda=0x%" PRIx64 ", personality=0x%" PRIx64 "",
+          "unwind_phase1(ex_ojb=%p): pc=0x%" PRIxPTR ", start_ip=0x%" PRIxPTR
+          ", func=%s, lsda=0x%" PRIxPTR ", personality=0x%" PRIxPTR "",
           (void *)exception_object, pc, frameInfo.start_ip, functionName,
           frameInfo.lsda, frameInfo.handler);
     }
 
     // If there is a personality routine, ask it if it will want to stop at
     // this frame.
     if (frameInfo.handler != 0) {
       __personality_routine p =
while (true) {
     if (_LIBUNWIND_TRACING_UNWINDING) {
       char functionBuf[512];
       const char *functionName = functionBuf;
       unw_word_t offset;
       if ((unw_get_proc_name(cursor, functionBuf, sizeof(functionBuf),
                              &offset) != UNW_ESUCCESS) ||
           (frameInfo.start_ip + offset > frameInfo.end_ip))
         functionName = ".anonymous.";
-      _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): start_ip=0x%" PRIx64
-                                 ", func=%s, sp=0x%" PRIx64 ", lsda=0x%" PRIx64
-                                 ", personality=0x%" PRIx64,
+      _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): start_ip=0x%" PRIxPTR
+                                 ", func=%s, sp=0x%" PRIxPTR ", lsda=0x%" PRIxPTR
+                                 ", personality=0x%" PRIxPTR,
                                  (void *)exception_object, frameInfo.start_ip,
                                  functionName, sp, frameInfo.lsda,
                                  frameInfo.handler);
     }
 
     // If there is a personality routine, tell it we are unwinding.
     if (frameInfo.handler != 0) {
       __personality_routine p =
if (frameInfo.handler != 0) {
             (void *)exception_object);
         // Personality routine says to transfer control to landing pad.
         // We may get control back if landing pad calls _Unwind_Resume().
         if (_LIBUNWIND_TRACING_UNWINDING) {
           unw_word_t pc;
           unw_get_reg(cursor, UNW_REG_IP, &pc);
           unw_get_reg(cursor, UNW_REG_SP, &sp);
           _LIBUNWIND_TRACE_UNWINDING("unwind_phase2(ex_ojb=%p): re-entering "
-                                     "user code with ip=0x%" PRIx64
-                                     ", sp=0x%" PRIx64,
+                                     "user code with ip=0x%" PRIxPTR
+                                     ", sp=0x%" PRIxPTR,
                                      (void *)exception_object, pc, sp);
         }
         unw_resume(cursor);
         // unw_resume() only returns if there was an error.
         return _URC_FATAL_PHASE2_ERROR;
       default:
         // Personality routine returned an unknown result code.
         _LIBUNWIND_DEBUG_LOG("personality function returned unknown result %d",
if (_LIBUNWIND_TRACING_UNWINDING) {
       char functionBuf[512];
       const char *functionName = functionBuf;
       unw_word_t offset;
       if ((unw_get_proc_name(cursor, functionBuf, sizeof(functionBuf),
                              &offset) != UNW_ESUCCESS) ||
           (frameInfo.start_ip + offset > frameInfo.end_ip))
         functionName = ".anonymous.";
       _LIBUNWIND_TRACE_UNWINDING(
-          "unwind_phase2_forced(ex_ojb=%p): start_ip=0x%" PRIx64
-          ", func=%s, lsda=0x%" PRIx64 ", personality=0x%" PRIx64,
+          "unwind_phase2_forced(ex_ojb=%p): start_ip=0x%" PRIxPTR
+          ", func=%s, lsda=0x%" PRIxPTR ", personality=0x%" PRIxPTR,
           (void *)exception_object, frameInfo.start_ip, functionName,
           frameInfo.lsda, frameInfo.handler);
     }
 
     // Call stop function at each frame.
     _Unwind_Action action =
         (_Unwind_Action)(_UA_FORCE_UNWIND | _UA_CLEANUP_PHASE);
     _Unwind_Reason_Code stopResult =

 }
 
 /// Called by personality handler during phase 2 to get register values.
 _LIBUNWIND_EXPORT uintptr_t
 _Unwind_GetGR(struct _Unwind_Context *context, int index) {
   unw_cursor_t *cursor = (unw_cursor_t *)context;
   unw_word_t result;
   unw_get_reg(cursor, index, &result);
-  _LIBUNWIND_TRACE_API("_Unwind_GetGR(context=%p, reg=%d) => 0x%" PRIx64,
-                       (void *)context, index, (uint64_t)result);
+  _LIBUNWIND_TRACE_API("_Unwind_GetGR(context=%p, reg=%d) => 0x%" PRIxPTR,
+                       (void *)context, index, result);
   return (uintptr_t)result;
 }
 
 /// Called by personality handler during phase 2 to alter register values.
 _LIBUNWIND_EXPORT void _Unwind_SetGR(struct _Unwind_Context *context, int index,
                                      uintptr_t value) {
-  _LIBUNWIND_TRACE_API("_Unwind_SetGR(context=%p, reg=%d, value=0x%0" PRIx64
+  _LIBUNWIND_TRACE_API("_Unwind_SetGR(context=%p, reg=%d, value=0x%0" PRIxPTR
                        ")",
-                       (void *)context, index, (uint64_t)value);
+                       (void *)context, index, value);
   unw_cursor_t *cursor = (unw_cursor_t *)context;
   unw_set_reg(cursor, index, value);
 }
 
 /// Called by personality handler during phase 2 to get instruction pointer.
 _LIBUNWIND_EXPORT uintptr_t _Unwind_GetIP(struct _Unwind_Context *context) {
   unw_cursor_t *cursor = (unw_cursor_t *)context;
   unw_word_t result;
   unw_get_reg(cursor, UNW_REG_IP, &result);
-  _LIBUNWIND_TRACE_API("_Unwind_GetIP(context=%p) => 0x%" PRIx64,
-                       (void *)context, (uint64_t)result);
+  _LIBUNWIND_TRACE_API("_Unwind_GetIP(context=%p) => 0x%" PRIxPTR,
+                       (void *)context, result);
   return (uintptr_t)result;
 }
 
 /// Called by personality handler during phase 2 to alter instruction pointer,
 /// such as setting where the landing pad is, so _Unwind_Resume() will
 /// start executing in the landing pad.
 _LIBUNWIND_EXPORT void _Unwind_SetIP(struct _Unwind_Context *context,
                                      uintptr_t value) {
-  _LIBUNWIND_TRACE_API("_Unwind_SetIP(context=%p, value=0x%0" PRIx64 ")",
-                       (void *)context, (uint64_t)value);
+  _LIBUNWIND_TRACE_API("_Unwind_SetIP(context=%p, value=0x%0" PRIxPTR ")",
+                       (void *)context, value);
   unw_cursor_t *cursor = (unw_cursor_t *)context;
   unw_set_reg(cursor, UNW_REG_IP, value);
 }
 
 #endif // !defined(_LIBUNWIND_ARM_EHABI) && !defined(__USING_SJLJ_EXCEPTIONS__)

src/libunwind.cpp

_LIBUNWIND_EXPORT int unw_get_reg(unw_cursor_t *cursor, unw_regnum_t regNum,
   }
   return UNW_EBADREG;
 }
 
 
 /// Set value of specified register at cursor position in stack frame.
 _LIBUNWIND_EXPORT int unw_set_reg(unw_cursor_t *cursor, unw_regnum_t regNum,
                                   unw_word_t value) {
-  _LIBUNWIND_TRACE_API("unw_set_reg(cursor=%p, regNum=%d, value=0x%llX)",
-                       static_cast<void *>(cursor), regNum, (long long)value);
+  _LIBUNWIND_TRACE_API("unw_set_reg(cursor=%p, regNum=%d, value=0x%" PRIXPTR ")",
+                       static_cast<void *>(cursor), regNum, value);
   typedef LocalAddressSpace::pint_t pint_t;
   AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
   if (co->validReg(regNum)) {
     co->setReg(regNum, (pint_t)value);
     // specical case altering IP to re-find info (being called by personality
     // function)
     if (regNum == UNW_REG_IP)
       co->setInfoBasedOnIPRegister(false);