[clang] [llvm] [AIX] Lower intrinsic __builtin_cpu_is into AIX platform-specific code. (PR #80069)

[Amy Kwan via cfe-commits]

================
@@ -126,4 +126,61 @@ PPC_LNX_CPU("power10",47)
 #undef PPC_LNX_DEFINE_OFFSETS
 #undef PPC_LNX_FEATURE
 #undef PPC_LNX_CPU
+
+// Definition of the following values are found in the AIX header
+// file: </usr/include/sys/systemcfg.h>.
+#ifndef AIX_POWERPC_USE_SYS_CONF
+  #define AIX_POWERPC_USE_SYS_CONF
+  #define AIX_SYSCON_IMPL_IDX 1
+  #define AIX_PPC7_VALUE 0x00008000
+  #define AIX_PPC8_VALUE 0x00010000
+  #define AIX_PPC9_VALUE 0x00020000
+  #define AIX_PPC10_VALUE 0x00040000
+
+  // Supported SUPPORT_METHOD values.
+  #define AIX_BUILTIN_PPC_TRUE 1
+  #define AIX_BUILTIN_PPC_FALSE 0
+  #define USE_SYS_CONF 2
+
+  // Supported COMPARE_OP values.
+  #define COMP_EQ  0
+
+#endif
+
+// The value of SUPPORT_METHOD can be AIX_BUILTIN_PPC_TRUE,
+// AIX_BUILTIN_PPC_FALSE, Or USE_SYS_CONF.
+// When the value of SUPPORT_METHOD is USE_SYS_CONF, the return value
+// depends on the result of comparing the data member of
+// _system_configuration specified by INDEX with a certain value.
+
+#ifndef PPC_AIX_CPU
+  #define PPC_AIX_CPU(NAME, SUPPORT_METHOD, INDEX, COMPARE_OP, VALUE)
+#endif
+
+// __builtin_cpu_is() is supported only on Power7 and up.
+PPC_AIX_CPU("power4",AIX_BUILTIN_PPC_FALSE,0,0,0)
+PPC_AIX_CPU("ppc970",AIX_BUILTIN_PPC_FALSE,0,0,0)
+PPC_AIX_CPU("power5",AIX_BUILTIN_PPC_FALSE,0,0,0)
+PPC_AIX_CPU("power5+",AIX_BUILTIN_PPC_FALSE,0,0,0)
+PPC_AIX_CPU("power6",AIX_BUILTIN_PPC_FALSE,0,0,0)
+PPC_AIX_CPU("ppc-cell-be",AIX_BUILTIN_PPC_FALSE,0,0,0)
+PPC_AIX_CPU("power6x",AIX_BUILTIN_PPC_FALSE,0,0,0)
+PPC_AIX_CPU("ppca2",AIX_BUILTIN_PPC_FALSE,0,0,0)
+PPC_AIX_CPU("ppc405",AIX_BUILTIN_PPC_FALSE,0,0,0)
+PPC_AIX_CPU("ppc440",AIX_BUILTIN_PPC_FALSE,0,0,0)
+PPC_AIX_CPU("ppc464",AIX_BUILTIN_PPC_FALSE,0,0,0)
+PPC_AIX_CPU("ppc476",AIX_BUILTIN_PPC_FALSE,0,0,0)
+PPC_AIX_CPU("power7",USE_SYS_CONF,AIX_SYSCON_IMPL_IDX,COMP_EQ,AIX_PPC7_VALUE)
+PPC_AIX_CPU("power8",USE_SYS_CONF,AIX_SYSCON_IMPL_IDX,COMP_EQ,AIX_PPC8_VALUE)
+PPC_AIX_CPU("power9",USE_SYS_CONF,AIX_SYSCON_IMPL_IDX,COMP_EQ,AIX_PPC9_VALUE)
+PPC_AIX_CPU("power10",USE_SYS_CONF,AIX_SYSCON_IMPL_IDX,COMP_EQ,AIX_PPC10_VALUE)
+#undef PPC_AIX_CPU
+
+// PPC_SYSTEMCONFIG_TYPE defines the IR data struture of the _system_conf
+// found in the AIX OS header file: </usr/include/sys/systemcfg.h>.
----------------
amy-kwan wrote:

```suggestion
// PPC_SYSTEMCONFIG_TYPE defines the IR data structure of _system_conf,
// that is found in the AIX OS header file: </usr/include/sys/systemcfg.h>.
```

https://github.com/llvm/llvm-project/pull/80069