[X86] Fix stack alignment on 32-bit Solaris/x86

On Solaris/x86, several hundred 32-bit tests `FAIL`, all in the same way:

  env ASAN_OPTIONS=halt_on_error=false ./halt_on_error_suppress_equal_pcs.cpp.tmp
  Segmentation Fault (core dumped)

They segfault during startup:

  Thread 2 received signal SIGSEGV, Segmentation fault.
  [Switching to Thread 1 (LWP 1)]
  0x080f21f0 in __sanitizer::internal_mmap(void*, unsigned long, int, int, int, unsigned long long) () at /vol/llvm/src/llvm-project/dist/compiler-rt/lib/sanitizer_common/sanitizer_solaris.cpp:65
  65	                             int prot, int flags, int fd, OFF_T offset) {
  1: x/i $pc
  => 0x80f21f0 <_ZN11__sanitizer13internal_mmapEPvmiiiy+16>:	movaps 0x30(%esp),%xmm0
  (gdb) p/x $esp
  $3 = 0xfeffd488

The problem is that `movaps` expects 16-byte alignment, while 32-bit Solaris/x86
only guarantees 4-byte alignment following the i386 psABI.

This patch updates `X86Subtarget::initSubtargetFeatures` accordingly,
handles Solaris/x86 in the corresponding testcase, and allows for some
variation in address alignment in
`compiler-rt/test/ubsan/TestCases/TypeCheck/vptr.cpp`.

Tested on `amd64-pc-solaris2.11` and `x86_64-pc-linux-gnu`.

Differential Revision: https://reviews.llvm.org/D87615

Author: rorth

compiler-rt/test/ubsan/TestCases/TypeCheck/vptr.cpp

@@ -162,7 +162,7 @@ int access_p(T *p, char type) {
   case 'm':
     // CHECK-MEMBER: vptr.cpp:[[@LINE+6]]:15: runtime error: member access within address [[PTR:0x[0-9a-f]*]] which does not point to an object of type 'T'
     // CHECK-MEMBER-NEXT: [[PTR]]: note: object is of type [[DYN_TYPE:'S'|'U']]
-    // CHECK-MEMBER-NEXT: {{^ .. .. .. ..  .. .. .. .. .. .. .. ..  }}
+    // CHECK-MEMBER-NEXT: {{^  ?.. .. .. ..  ?.. .. .. ..  ?.. .. .. ..  ?}}
     // CHECK-MEMBER-NEXT: {{^              \^~~~~~~~~~~(~~~~~~~~~~~~)? *$}}
     // CHECK-MEMBER-NEXT: {{^              vptr for}} [[DYN_TYPE]]
     // CHECK-Linux-MEMBER: #0 {{.*}}access_p{{.*}}vptr.cpp:[[@LINE+1]]
@@ -178,7 +178,7 @@ int access_p(T *p, char type) {
   case 'f':
     // CHECK-MEMFUN: vptr.cpp:[[@LINE+6]]:15: runtime error: member call on address [[PTR:0x[0-9a-f]*]] which does not point to an object of type 'T'
     // CHECK-MEMFUN-NEXT: [[PTR]]: note: object is of type [[DYN_TYPE:'S'|'U']]
-    // CHECK-MEMFUN-NEXT: {{^ .. .. .. ..  .. .. .. .. .. .. .. ..  }}
+    // CHECK-MEMFUN-NEXT: {{^  ?.. .. .. ..  ?.. .. .. ..  ?.. .. .. ..  ?}}
     // CHECK-MEMFUN-NEXT: {{^              \^~~~~~~~~~~(~~~~~~~~~~~~)? *$}}
     // CHECK-MEMFUN-NEXT: {{^              vptr for}} [[DYN_TYPE]]
     // TODO: Add check for stacktrace here.
@@ -196,7 +196,7 @@ int access_p(T *p, char type) {
   case 'c':
     // CHECK-DOWNCAST: vptr.cpp:[[@LINE+6]]:11: runtime error: downcast of address [[PTR:0x[0-9a-f]*]] which does not point to an object of type 'T'
     // CHECK-DOWNCAST-NEXT: [[PTR]]: note: object is of type [[DYN_TYPE:'S'|'U']]
-    // CHECK-DOWNCAST-NEXT: {{^ .. .. .. ..  .. .. .. .. .. .. .. ..  }}
+    // CHECK-DOWNCAST-NEXT: {{^  ?.. .. .. ..  ?.. .. .. ..  ?.. .. .. ..  ?}}
     // CHECK-DOWNCAST-NEXT: {{^              \^~~~~~~~~~~(~~~~~~~~~~~~)? *$}}
     // CHECK-DOWNCAST-NEXT: {{^              vptr for}} [[DYN_TYPE]]
     // CHECK-Linux-DOWNCAST: #0 {{.*}}access_p{{.*}}vptr.cpp:[[@LINE+1]]

llvm/lib/Target/X86/X86Subtarget.cpp

@@ -258,12 +258,13 @@ void X86Subtarget::initSubtargetFeatures(StringRef CPU, StringRef TuneCPU,
     report_fatal_error("64-bit code requested on a subtarget that doesn't "
                        "support it!");
 
-  // Stack alignment is 16 bytes on Darwin, Linux, kFreeBSD and Solaris (both
-  // 32 and 64 bit) and for all 64-bit targets.
+  // Stack alignment is 16 bytes on Darwin, Linux, kFreeBSD and for all
+  // 64-bit targets.  On Solaris (32-bit), stack alignment is 4 bytes
+  // following the i386 psABI, while on Illumos it is always 16 bytes.
   if (StackAlignOverride)
     stackAlignment = *StackAlignOverride;
-  else if (isTargetDarwin() || isTargetLinux() || isTargetSolaris() ||
-           isTargetKFreeBSD() || In64BitMode)
+  else if (isTargetDarwin() || isTargetLinux() || isTargetKFreeBSD() ||
+           In64BitMode)
     stackAlignment = Align(16);
 
   // Consume the vector width attribute or apply any target specific limit.

llvm/test/CodeGen/X86/stack-align2.ll

@@ -2,10 +2,12 @@
 ; RUN: llc < %s -mcpu=generic -mtriple=i386-kfreebsd | FileCheck %s -check-prefix=KFREEBSD-I386
 ; RUN: llc < %s -mcpu=generic -mtriple=i386-netbsd | FileCheck %s -check-prefix=NETBSD-I386
 ; RUN: llc < %s -mcpu=generic -mtriple=i686-apple-darwin8 | FileCheck %s -check-prefix=DARWIN-I386
+; RUN: llc < %s -mcpu=generic -mtriple=i386-pc-solaris2.11 | FileCheck %s -check-prefix=SOLARIS-I386
 ; RUN: llc < %s -mcpu=generic -mtriple=x86_64-linux | FileCheck %s -check-prefix=LINUX-X86_64
 ; RUN: llc < %s -mcpu=generic -mtriple=x86_64-kfreebsd | FileCheck %s -check-prefix=KFREEBSD-X86_64
 ; RUN: llc < %s -mcpu=generic -mtriple=x86_64-netbsd | FileCheck %s -check-prefix=NETBSD-X86_64
 ; RUN: llc < %s -mcpu=generic -mtriple=x86_64-apple-darwin8 | FileCheck %s -check-prefix=DARWIN-X86_64
+; RUN: llc < %s -mcpu=generic -mtriple=x86_64-pc-solaris2.11 | FileCheck %s -check-prefix=SOLARIS-X86_64
 
 define i32 @test() nounwind {
 entry:
@@ -15,14 +17,17 @@ entry:
 ; LINUX-I386:     subl	$12, %esp
 ; KFREEBSD-I386:  subl	$12, %esp
 ; DARWIN-I386:    subl	$12, %esp
-; NETBSD-I386-NOT: subl	{{.*}}, %esp
+; NETBSD-I386-NOT:  subl	{{.*}}, %esp
+; SOLARIS-I386-NOT: subl	{{.*}}, %esp
 
 ; LINUX-X86_64:      pushq %{{.*}}
 ; LINUX-X86_64-NOT:  subq	{{.*}}, %rsp
 ; DARWIN-X86_64:     pushq %{{.*}}
 ; DARWIN-X86_64-NOT: subq	{{.*}}, %rsp
 ; NETBSD-X86_64:     pushq %{{.*}}
 ; NETBSD-X86_64-NOT: subq	{{.*}}, %rsp
+; SOLARIS-X86_64:     pushq %{{.*}}
+; SOLARIS-X86_64-NOT: subq	{{.*}}, %rsp
 ; KFREEBSD-X86_64:     pushq %{{.*}}
 ; KFREEBSD-X86_64-NOT: subq	{{.*}}, %rsp
 }