Revert "[compiler-rt][X86] Use functions in cpuid.h instead of inline assembly (#97877)"

This reverts commit 19cf8de.

This was causing quite a few buildbot failures (see the PR description).
Reverting for now while I have time to sort it out. Seems like it should
just be conditional preprocessor macros for X86 however.

Author: boomanaiden154

compiler-rt/lib/builtins/cpu_model/x86.c

@@ -23,10 +23,6 @@
 
 #include <assert.h>
 
-#if defined(__GNUC__) || defined(__clang__)
-#include <cpuid.h>
-#endif
-
 #ifdef _MSC_VER
 #include <intrin.h>
 #endif
@@ -228,6 +224,38 @@ enum ProcessorFeatures {
   CPU_FEATURE_MAX
 };
 
+// The check below for i386 was copied from clang's cpuid.h (__get_cpuid_max).
+// Check motivated by bug reports for OpenSSL crashing on CPUs without CPUID
+// support. Consequently, for i386, the presence of CPUID is checked first
+// via the corresponding eflags bit.
+static bool isCpuIdSupported(void) {
+#if defined(__GNUC__) || defined(__clang__)
+#if defined(__i386__)
+  int __cpuid_supported;
+  __asm__("  pushfl\n"
+          "  popl   %%eax\n"
+          "  movl   %%eax,%%ecx\n"
+          "  xorl   $0x00200000,%%eax\n"
+          "  pushl  %%eax\n"
+          "  popfl\n"
+          "  pushfl\n"
+          "  popl   %%eax\n"
+          "  movl   $0,%0\n"
+          "  cmpl   %%eax,%%ecx\n"
+          "  je     1f\n"
+          "  movl   $1,%0\n"
+          "1:"
+          : "=r"(__cpuid_supported)
+          :
+          : "eax", "ecx");
+  if (!__cpuid_supported)
+    return false;
+#endif
+  return true;
+#endif
+  return true;
+}
+
 // This code is copied from lib/Support/Host.cpp.
 // Changes to either file should be mirrored in the other.
 
@@ -236,7 +264,25 @@ enum ProcessorFeatures {
 static bool getX86CpuIDAndInfo(unsigned value, unsigned *rEAX, unsigned *rEBX,
                                unsigned *rECX, unsigned *rEDX) {
 #if defined(__GNUC__) || defined(__clang__)
-  return !__get_cpuid(value, rEAX, rEBX, rECX, rEDX);
+#if defined(__x86_64__)
+  // gcc doesn't know cpuid would clobber ebx/rbx. Preserve it manually.
+  // FIXME: should we save this for Clang?
+  __asm__("movq\t%%rbx, %%rsi\n\t"
+          "cpuid\n\t"
+          "xchgq\t%%rbx, %%rsi\n\t"
+          : "=a"(*rEAX), "=S"(*rEBX), "=c"(*rECX), "=d"(*rEDX)
+          : "a"(value));
+  return false;
+#elif defined(__i386__)
+  __asm__("movl\t%%ebx, %%esi\n\t"
+          "cpuid\n\t"
+          "xchgl\t%%ebx, %%esi\n\t"
+          : "=a"(*rEAX), "=S"(*rEBX), "=c"(*rECX), "=d"(*rEDX)
+          : "a"(value));
+  return false;
+#else
+  return true;
+#endif
 #elif defined(_MSC_VER)
   // The MSVC intrinsic is portable across x86 and x64.
   int registers[4];
@@ -257,12 +303,26 @@ static bool getX86CpuIDAndInfo(unsigned value, unsigned *rEAX, unsigned *rEBX,
 static bool getX86CpuIDAndInfoEx(unsigned value, unsigned subleaf,
                                  unsigned *rEAX, unsigned *rEBX, unsigned *rECX,
                                  unsigned *rEDX) {
-  // TODO(boomanaiden154): When the minimum toolchain versions for gcc and clang
-  // are such that __cpuidex is defined within cpuid.h for both, we can remove
-  // the __get_cpuid_count function and share the MSVC implementation between
-  // all three.
 #if defined(__GNUC__) || defined(__clang__)
-  return !__get_cpuid_count(value, subleaf, rEAX, rEBX, rECX, rEDX);
+#if defined(__x86_64__)
+  // gcc doesn't know cpuid would clobber ebx/rbx. Preserve it manually.
+  // FIXME: should we save this for Clang?
+  __asm__("movq\t%%rbx, %%rsi\n\t"
+          "cpuid\n\t"
+          "xchgq\t%%rbx, %%rsi\n\t"
+          : "=a"(*rEAX), "=S"(*rEBX), "=c"(*rECX), "=d"(*rEDX)
+          : "a"(value), "c"(subleaf));
+  return false;
+#elif defined(__i386__)
+  __asm__("movl\t%%ebx, %%esi\n\t"
+          "cpuid\n\t"
+          "xchgl\t%%ebx, %%esi\n\t"
+          : "=a"(*rEAX), "=S"(*rEBX), "=c"(*rECX), "=d"(*rEDX)
+          : "a"(value), "c"(subleaf));
+  return false;
+#else
+  return true;
+#endif
 #elif defined(_MSC_VER)
   int registers[4];
   __cpuidex(registers, value, subleaf);
@@ -278,9 +338,6 @@ static bool getX86CpuIDAndInfoEx(unsigned value, unsigned subleaf,
 
 // Read control register 0 (XCR0). Used to detect features such as AVX.
 static bool getX86XCR0(unsigned *rEAX, unsigned *rEDX) {
-  // TODO(boomanaiden154): When the minimum toolchain versions for gcc and clang
-  // are such that _xgetbv is supported by both, we can unify the implementation
-  // with MSVC and remove all inline assembly.
 #if defined(__GNUC__) || defined(__clang__)
   // Check xgetbv; this uses a .byte sequence instead of the instruction
   // directly because older assemblers do not include support for xgetbv and
@@ -1051,7 +1108,8 @@ int CONSTRUCTOR_ATTRIBUTE __cpu_indicator_init(void) {
   if (__cpu_model.__cpu_vendor)
     return 0;
 
-  if (getX86CpuIDAndInfo(0, &MaxLeaf, &Vendor, &ECX, &EDX) || MaxLeaf < 1) {
+  if (!isCpuIdSupported() ||
+      getX86CpuIDAndInfo(0, &MaxLeaf, &Vendor, &ECX, &EDX) || MaxLeaf < 1) {
     __cpu_model.__cpu_vendor = VENDOR_OTHER;
     return -1;
   }

llvm/lib/TargetParser/Host.cpp

@@ -50,9 +50,6 @@
 #if defined(__sun__) && defined(__svr4__)
 #include <kstat.h>
 #endif
-#if defined(__GNUC__) || defined(__clang__)
-#include <cpuid.h>
-#endif
 
 #define DEBUG_TYPE "host-detection"
 
@@ -524,15 +521,68 @@ StringRef sys::detail::getHostCPUNameForBPF() {
 #endif
 }
 
-#if defined(__i386__) || defined(_M_IX86) || defined(__x86_64__) ||            \
-    defined(_M_X64)
+#if defined(__i386__) || defined(_M_IX86) || \
+    defined(__x86_64__) || defined(_M_X64)
+
+// The check below for i386 was copied from clang's cpuid.h (__get_cpuid_max).
+// Check motivated by bug reports for OpenSSL crashing on CPUs without CPUID
+// support. Consequently, for i386, the presence of CPUID is checked first
+// via the corresponding eflags bit.
+// Removal of cpuid.h header motivated by PR30384
+// Header cpuid.h and method __get_cpuid_max are not used in llvm, clang, openmp
+// or test-suite, but are used in external projects e.g. libstdcxx
+static bool isCpuIdSupported() {
+#if defined(__GNUC__) || defined(__clang__)
+#if defined(__i386__)
+  int __cpuid_supported;
+  __asm__("  pushfl\n"
+          "  popl   %%eax\n"
+          "  movl   %%eax,%%ecx\n"
+          "  xorl   $0x00200000,%%eax\n"
+          "  pushl  %%eax\n"
+          "  popfl\n"
+          "  pushfl\n"
+          "  popl   %%eax\n"
+          "  movl   $0,%0\n"
+          "  cmpl   %%eax,%%ecx\n"
+          "  je     1f\n"
+          "  movl   $1,%0\n"
+          "1:"
+          : "=r"(__cpuid_supported)
+          :
+          : "eax", "ecx");
+  if (!__cpuid_supported)
+    return false;
+#endif
+  return true;
+#endif
+  return true;
+}
 
 /// getX86CpuIDAndInfo - Execute the specified cpuid and return the 4 values in
 /// the specified arguments.  If we can't run cpuid on the host, return true.
 static bool getX86CpuIDAndInfo(unsigned value, unsigned *rEAX, unsigned *rEBX,
                                unsigned *rECX, unsigned *rEDX) {
 #if defined(__GNUC__) || defined(__clang__)
-  return !__get_cpuid(value, rEAX, rEBX, rECX, rEDX);
+#if defined(__x86_64__)
+  // gcc doesn't know cpuid would clobber ebx/rbx. Preserve it manually.
+  // FIXME: should we save this for Clang?
+  __asm__("movq\t%%rbx, %%rsi\n\t"
+          "cpuid\n\t"
+          "xchgq\t%%rbx, %%rsi\n\t"
+          : "=a"(*rEAX), "=S"(*rEBX), "=c"(*rECX), "=d"(*rEDX)
+          : "a"(value));
+  return false;
+#elif defined(__i386__)
+  __asm__("movl\t%%ebx, %%esi\n\t"
+          "cpuid\n\t"
+          "xchgl\t%%ebx, %%esi\n\t"
+          : "=a"(*rEAX), "=S"(*rEBX), "=c"(*rECX), "=d"(*rEDX)
+          : "a"(value));
+  return false;
+#else
+  return true;
+#endif
 #elif defined(_MSC_VER)
   // The MSVC intrinsic is portable across x86 and x64.
   int registers[4];
@@ -559,6 +609,9 @@ VendorSignatures getVendorSignature(unsigned *MaxLeaf) {
   else
     *MaxLeaf = 0;
 
+  if (!isCpuIdSupported())
+    return VendorSignatures::UNKNOWN;
+
   if (getX86CpuIDAndInfo(0, MaxLeaf, &EBX, &ECX, &EDX) || *MaxLeaf < 1)
     return VendorSignatures::UNKNOWN;
 
@@ -586,12 +639,26 @@ using namespace llvm::sys::detail::x86;
 static bool getX86CpuIDAndInfoEx(unsigned value, unsigned subleaf,
                                  unsigned *rEAX, unsigned *rEBX, unsigned *rECX,
                                  unsigned *rEDX) {
-  // TODO(boomanaiden154): When the minimum toolchain versions for gcc and clang
-  // are such that __cpuidex is defined within cpuid.h for both, we can remove
-  // the __get_cpuid_count function and share the MSVC implementation between
-  // all three.
 #if defined(__GNUC__) || defined(__clang__)
-  return !__get_cpuid_count(value, subleaf, rEAX, rEBX, rECX, rEDX);
+#if defined(__x86_64__)
+  // gcc doesn't know cpuid would clobber ebx/rbx. Preserve it manually.
+  // FIXME: should we save this for Clang?
+  __asm__("movq\t%%rbx, %%rsi\n\t"
+          "cpuid\n\t"
+          "xchgq\t%%rbx, %%rsi\n\t"
+          : "=a"(*rEAX), "=S"(*rEBX), "=c"(*rECX), "=d"(*rEDX)
+          : "a"(value), "c"(subleaf));
+  return false;
+#elif defined(__i386__)
+  __asm__("movl\t%%ebx, %%esi\n\t"
+          "cpuid\n\t"
+          "xchgl\t%%ebx, %%esi\n\t"
+          : "=a"(*rEAX), "=S"(*rEBX), "=c"(*rECX), "=d"(*rEDX)
+          : "a"(value), "c"(subleaf));
+  return false;
+#else
+  return true;
+#endif
 #elif defined(_MSC_VER)
   int registers[4];
   __cpuidex(registers, value, subleaf);
@@ -607,9 +674,6 @@ static bool getX86CpuIDAndInfoEx(unsigned value, unsigned subleaf,
 
 // Read control register 0 (XCR0). Used to detect features such as AVX.
 static bool getX86XCR0(unsigned *rEAX, unsigned *rEDX) {
-  // TODO(boomanaiden154): When the minimum toolchain versions for gcc and clang
-  // are such that _xgetbv is supported by both, we can unify the implementation
-  // with MSVC and remove all inline assembly.
 #if defined(__GNUC__) || defined(__clang__)
   // Check xgetbv; this uses a .byte sequence instead of the instruction
   // directly because older assemblers do not include support for xgetbv and