[AIX] Let alloca return 16 bytes alignment

On AIX, to support vector types, which should always be 16 bytes aligned,
we set alloca to return 16 bytes aligned memory space.

Differential Revision: https://reviews.llvm.org/D89910

Author: xling-liao

clang/lib/Basic/Targets/PPC.h

@@ -370,7 +370,6 @@ class LLVM_LIBRARY_VISIBILITY PPC32TargetInfo : public PPCTargetInfo {
       SizeType = UnsignedLong;
       PtrDiffType = SignedLong;
       IntPtrType = SignedLong;
-      SuitableAlign = 64;
       LongDoubleWidth = 64;
       LongDoubleAlign = DoubleAlign = 32;
       LongDoubleFormat = &llvm::APFloat::IEEEdouble();
@@ -409,7 +408,6 @@ class LLVM_LIBRARY_VISIBILITY PPC64TargetInfo : public PPCTargetInfo {
     if (Triple.isOSAIX()) {
       // TODO: Set appropriate ABI for AIX platform.
       DataLayout = "E-m:a-i64:64-n32:64";
-      SuitableAlign = 64;
       LongDoubleWidth = 64;
       LongDoubleAlign = DoubleAlign = 32;
       LongDoubleFormat = &llvm::APFloat::IEEEdouble();

clang/test/CodeGen/aix_alloca_align.c

@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -triple=powerpc-ibm-aix-xcoff -S -emit-llvm < %s | \
+// RUN:   FileCheck --check-prefix=32BIT %s
+
+// RUN: %clang_cc1 -triple=powerpc64-ibm-aix-xcoff -S -emit-llvm < %s | \
+// RUN:   FileCheck --check-prefix=64BIT %s
+
+typedef __SIZE_TYPE__ size_t;
+extern void *alloca(size_t __size) __attribute__((__nothrow__));
+
+void foo() {
+  char *ptr1 = (char *)alloca(sizeof(char) * 9);
+  char *ptr2 = (char *)alloca(sizeof(char) * 32);
+}
+
+// 32BIT: %0 = alloca i8, i32 9, align 16
+// 32BIT: %1 = alloca i8, i32 32, align 16
+
+// 64BIT: %0 = alloca i8, i64 9, align 16
+// 64BIT: %1 = alloca i8, i64 32, align 16

clang/test/Preprocessor/init-ppc.c

@@ -398,7 +398,7 @@
 // PPC-AIX:#define _LONG_LONG 1
 // PPC-AIX-NOT:#define _LP64 1
 // PPC-AIX:#define _POWER 1
-// PPC-AIX:#define __BIGGEST_ALIGNMENT__ 8
+// PPC-AIX:#define __BIGGEST_ALIGNMENT__ 16
 // PPC-AIX:#define __BIG_ENDIAN__ 1
 // PPC-AIX:#define __BYTE_ORDER__ __ORDER_BIG_ENDIAN__
 // PPC-AIX:#define __CHAR16_TYPE__ unsigned short

clang/test/Preprocessor/init-ppc64.c

@@ -666,7 +666,7 @@
 // PPC64-AIX:#define _LP64 1
 // PPC64-AIX:#define _POWER 1
 // PPC64-AIX:#define __64BIT__ 1
-// PPC64-AIX:#define __BIGGEST_ALIGNMENT__ 8
+// PPC64-AIX:#define __BIGGEST_ALIGNMENT__ 16
 // PPC64-AIX:#define __BIG_ENDIAN__ 1
 // PPC64-AIX:#define __BYTE_ORDER__ __ORDER_BIG_ENDIAN__
 // PPC64-AIX:#define __CHAR16_TYPE__ unsigned short