rt: Add architecture-specific general-purpose register definitions

This will be used for stack crawling, which in turn will be used for GC and
unwinding.

mk/rt.mk

@@ -72,7 +72,8 @@ RUNTIME_CS_$(1) := \
               rt/rust_box_annihilator.cpp \
               rt/memory_region.cpp \
               rt/boxed_region.cpp \
-              rt/arch/$$(HOST_$(1))/context.cpp
+              rt/arch/$$(HOST_$(1))/context.cpp \
+              rt/arch/$$(HOST_$(1))/gpr.cpp
 
 RUNTIME_S_$(1) := rt/arch/$$(HOST_$(1))/_context.S \
                   rt/arch/$$(HOST_$(1))/ccall.S \

src/rt/arch/i386/gpr.cpp

@@ -0,0 +1,13 @@
+#include "gpr.h"
+
+#define LOAD(rn) do { \
+    uintptr_t tmp; \
+    asm("movl %%" #rn ",%0" : "=r" (tmp) :); \
+    this->rn = tmp; \
+} while (0)
+
+void rust_gpr::load() {
+    LOAD(eax); LOAD(ebx); LOAD(ecx); LOAD(edx);
+    LOAD(esi); LOAD(edi); LOAD(ebp); LOAD(esi);
+}
+

src/rt/arch/i386/gpr.h

@@ -0,0 +1,22 @@
+// General-purpose registers. This structure is used during stack crawling.
+
+#ifndef GPR_H
+#define GPR_H
+
+#include "rust_gpr_base.h"
+
+class rust_gpr : public rust_gpr_base {
+public:
+    uintptr_t eax, ebx, ecx, edx, esi, edi, ebp, eip;
+
+    inline uintptr_t get_fp() { return ebp; }
+    inline uintptr_t get_ip() { return eip; }
+
+    inline void set_fp(uintptr_t new_fp) { ebp = new_fp; }
+    inline void set_ip(uintptr_t new_ip) { eip = new_ip; }
+
+    void load();
+};
+
+#endif
+

src/rt/arch/x86_64/gpr.cpp

@@ -0,0 +1,15 @@
+#include "gpr.h"
+
+#define LOAD(rn) do { \
+    uintptr_t tmp; \
+    asm("movq %%" #rn ",%0" : "=r" (tmp) :); \
+    this->rn = tmp; \
+} while (0)
+
+void rust_gpr::load() {
+    LOAD(rax); LOAD(rbx); LOAD(rcx); LOAD(rdx);
+    LOAD(rsi); LOAD(rdi); LOAD(rbp); LOAD(rsi);
+    LOAD(r8);  LOAD(r9);  LOAD(r10); LOAD(r11);
+    LOAD(r12); LOAD(r13); LOAD(r14); LOAD(r15);
+}
+

src/rt/arch/x86_64/gpr.h

@@ -0,0 +1,23 @@
+// General-purpose registers. This structure is used during stack crawling.
+
+#ifndef GPR_H
+#define GPR_H
+
+#include "rust_gpr_base.h"
+
+class rust_gpr : public rust_gpr_base {
+public:
+    uintptr_t rax, rbx, rcx, rdx, rsi, rdi, rbp, rip;
+    uintptr_t  r8,  r9, r10, r11, r12, r13, r14, r15;
+
+    inline uintptr_t get_fp() { return rbp; }
+    inline uintptr_t get_ip() { return rip; }
+
+    inline void set_fp(uintptr_t new_fp) { rbp = new_fp; }
+    inline void set_ip(uintptr_t new_ip) { rip = new_ip; }
+
+    void load();
+};
+
+#endif
+

src/rt/rust_gpr_base.h

@@ -0,0 +1,24 @@
+// Base class for architecture-specific general-purpose registers. This
+// structure is used during stack crawling.
+
+#ifndef GPR_BASE_H
+#define GPR_BASE_H
+
+#include <stdint.h>
+
+class rust_gpr_base {
+public:
+    // Returns the value of a register by number.
+    inline uintptr_t &get(uint32_t i) {
+        return reinterpret_cast<uintptr_t *>(this)[i];
+    }
+
+    // Sets the value of a register by number.
+    inline void set(uint32_t i, uintptr_t val) {
+        reinterpret_cast<uintptr_t *>(this)[i] = val;
+    }
+};
+
+
+#endif
+