[lldb] [lit] Introduce tests for writing x86 general-purpose registers

[mgorny]

Summary

Introduce two initial tests for 'register write' command. The tests
first clobber x86 general purpose registers, then call int3 to let lldb
write to them, then print the new values. FileCheck takes care of
verifying whether correct values were written.

[labath]

This is great stuff. Thanks for doing this.

lit/Register/Inputs/x86-64-gp-write.cpp

+#include <cinttypes>
+#include <cstdint>
+#include <cstdio>
+
+int main() {
+  constexpr uint64_t fill = 0x0F0F0F0F0F0F0F0F;
+
+  uint64_t rax, rbx, rcx, rdx, rsp, rbp, rsi, rdi;
+
+  asm volatile(
+    // save rsp & rbp
+    "movq    %%rsp, %%mm0\n\t"
+    "movq    %%rbp, %%mm1\n\t"
+    "\n\t"
+    "movq    %8, %%rax\n\t"
+    "movq    %8, %%rbx\n\t"
+    "movq    %8, %%rcx\n\t"
+    "movq    %8, %%rdx\n\t"
+    "movq    %8, %%rsp\n\t"
+    "movq    %8, %%rbp\n\t"
+    "movq    %8, %%rsi\n\t"
+    "movq    %8, %%rdi\n\t"
+    "\n\t"
+    "int3\n\t"
+    "\n\t"
+    "movq    %%rax, %0\n\t"
+    "movq    %%rbx, %1\n\t"
+    "movq    %%rcx, %2\n\t"
+    "movq    %%rdx, %3\n\t"
+    "movq    %%rsp, %4\n\t"
+    "movq    %%rbp, %5\n\t"
+    "movq    %%rsi, %6\n\t"
+    "movq    %%rdi, %7\n\t"
+    "\n\t"
+    // restore rsp & rbp
+    "movq    %%mm0, %%rsp\n\t"
+    "movq    %%mm1, %%rbp\n\t"
+    : "=r"(rax), "=r"(rbx), "=r"(rcx), "=r"(rdx), "=r"(rsp), "=r"(rbp),
+      "=r"(rsi), "=r"(rdi)
+    : "g"(fill)
+    : "%rax", "%rbx", "%rcx", "%rdx", "%rsp", "%rbp", "%rsi", "%rdi", "%mm0",
+      "%mm1"
+  );
+
+  printf("rax = 0x%016" PRIx64 "\n", rax);
+  printf("rbx = 0x%016" PRIx64 "\n", rbx);
+  printf("rcx = 0x%016" PRIx64 "\n", rcx);
+  printf("rdx = 0x%016" PRIx64 "\n", rdx);
+  printf("rsp = 0x%016" PRIx64 "\n", rsp);
+  printf("rbp = 0x%016" PRIx64 "\n", rbp);
+  printf("rsi = 0x%016" PRIx64 "\n", rsi);
+  printf("rdi = 0x%016" PRIx64 "\n", rdi);
+
+  return 0;
+}

lit/Register/Inputs/x86-gp-write.cpp

+#include <cinttypes>
+#include <cstdint>
+#include <cstdio>
+
+int main() {
+  constexpr uint32_t fill = 0x0F0F0F0F;
+
+  uint32_t eax, ebx, ecx, edx, esp, ebp, esi, edi;
+
+  asm volatile(
+    // save esp & ebp
+    "movd    %%esp, %%mm0\n\t"
+    "movd    %%ebp, %%mm1\n\t"
+    "\n\t"
+    "movl    %8, %%eax\n\t"
+    "movl    %8, %%ebx\n\t"
+    "movl    %8, %%ecx\n\t"
+    "movl    %8, %%edx\n\t"
+    "movl    %8, %%esp\n\t"
+    "movl    %8, %%ebp\n\t"
+    "movl    %8, %%esi\n\t"
+    "movl    %8, %%edi\n\t"
+    "\n\t"
+    "int3\n\t"
+    "\n\t"
+    // first save new esp & ebp, and restore their original values, so that
+    // we can output values via memory
+    "movd    %%esp, %%mm2\n\t"
+    "movd    %%ebp, %%mm3\n\t"
+    "movd    %%mm0, %%esp\n\t"
+    "movd    %%mm1, %%ebp\n\t"
+    "\n\t"
+    // output values via memory
+    "movl    %%eax, %0\n\t"
+    "movl    %%ebx, %1\n\t"
+    "movl    %%ecx, %2\n\t"
+    "movl    %%edx, %3\n\t"
+    "movl    %%esi, %6\n\t"
+    "movl    %%edi, %7\n\t"
+    "\n\t"
+    // output saved esp & ebp
+    "movd    %%mm2, %4\n\t"
+    "movd    %%mm3, %5\n\t"
+    : "=m"(eax), "=m"(ebx), "=m"(ecx), "=m"(edx), "=a"(esp), "=b"(ebp),
+      "=m"(esi), "=m"(edi)
+    : "i"(fill)
+    : "%ecx", "%edx", "%esp", "%ebp", "%esi", "%edi", "%mm0", "%mm1", "%mm2",
+      "%mm3"
+  );
+
+  printf("eax = 0x%08" PRIx32 "\n", eax);
+  printf("ebx = 0x%08" PRIx32 "\n", ebx);
+  printf("ecx = 0x%08" PRIx32 "\n", ecx);
+  printf("edx = 0x%08" PRIx32 "\n", edx);
+  printf("esp = 0x%08" PRIx32 "\n", esp);
+  printf("ebp = 0x%08" PRIx32 "\n", ebp);
+  printf("esi = 0x%08" PRIx32 "\n", esi);
+  printf("edi = 0x%08" PRIx32 "\n", edi);
+
+  return 0;
+}

lit/Register/x86-64-gp-write.test

+# XFAIL: system-windows
+# REQUIRES: native && target-x86_64
+# RUN: %clangxx -fomit-frame-pointer %p/Inputs/x86-64-gp-read.cpp -o %t
+# RUN: %lldb -b -s %s %t | FileCheck %s
+process launch
+
+register write rax 0x0102030405060708
+register write rbx 0x1112131415161718
+register write rcx 0x2122232425262728
+register write rdx 0x3132333435363738
+register write rsp 0x4142434445464748
+register write rbp 0x5152535455565758
+register write rsi 0x6162636465666768
+register write rdi 0x7172737475767778
+
+process continue
+# CHECK-DAG: rax = 0x0102030405060708
+# CHECK-DAG: rbx = 0x1112131415161718
+# CHECK-DAG: rcx = 0x2122232425262728
+# CHECK-DAG: rdx = 0x3132333435363738
+# CHECK-DAG: rsp = 0x4142434445464748
+# CHECK-DAG: rbp = 0x5152535455565758
+# CHECK-DAG: rsi = 0x6162636465666768
+# CHECK-DAG: rdi = 0x7172737475767778
+
+# CHECK: Process {{[0-9]+}} exited with status = 0

lit/Register/x86-gp-write.test

+# XFAIL: system-windows
+# REQUIRES: native && target-x86
+# RUN: %clangxx -fomit-frame-pointer %p/Inputs/x86-64-gp-read.cpp -o %t
+# RUN: %lldb -b -s %s %t | FileCheck %s
+process launch
+
+register write eax 0x01020304
+register write ebx 0x11121314
+register write ecx 0x21222324
+register write edx 0x31323334
+register write esp 0x41424344
+register write ebp 0x51525354
+register write esi 0x61626364
+register write edi 0x71727374
+
+process continue
+# CHECK-DAG: eax = 0x01020304
+# CHECK-DAG: ebx = 0x11121314
+# CHECK-DAG: ecx = 0x21222324
+# CHECK-DAG: edx = 0x31323334
+# CHECK-DAG: esp = 0x41424344
+# CHECK-DAG: ebp = 0x51525354
+# CHECK-DAG: esi = 0x61626364
+# CHECK-DAG: edi = 0x71727374
+
+# CHECK: Process {{[0-9]+}} exited with status = 0