[SPIR] Set MaxAtomicInlineWidth minimum size to 32 for spir32 and 64 for spir64 (#148997)

Set MaxAtomicInlineWidth the same way as SPIR-V targets in 3cfd0c0.
This PR fixes build warning in scoped atomic built-in in #146814:
`warning: large atomic operation may incur significant performance
penalty; ; the access size (2 bytes) exceeds the max lock-free size (0
bytes) [-Watomic-alignment]`

Author: wenju-he

clang/lib/Basic/Targets/SPIR.h

@@ -264,6 +264,9 @@ class LLVM_LIBRARY_VISIBILITY SPIR32TargetInfo : public SPIRTargetInfo {
     PointerWidth = PointerAlign = 32;
     SizeType = TargetInfo::UnsignedInt;
     PtrDiffType = IntPtrType = TargetInfo::SignedInt;
+    // SPIR32 has support for atomic ops if atomic extension is enabled.
+    // Take the maximum because it's possible the Host supports wider types.
+    MaxAtomicInlineWidth = std::max<unsigned char>(MaxAtomicInlineWidth, 32);
     resetDataLayout("e-p:32:32-i64:64-v16:16-v24:32-v32:32-v48:64-"
                     "v96:128-v192:256-v256:256-v512:512-v1024:1024-G1");
   }
@@ -281,6 +284,9 @@ class LLVM_LIBRARY_VISIBILITY SPIR64TargetInfo : public SPIRTargetInfo {
     PointerWidth = PointerAlign = 64;
     SizeType = TargetInfo::UnsignedLong;
     PtrDiffType = IntPtrType = TargetInfo::SignedLong;
+    // SPIR64 has support for atomic ops if atomic extension is enabled.
+    // Take the maximum because it's possible the Host supports wider types.
+    MaxAtomicInlineWidth = std::max<unsigned char>(MaxAtomicInlineWidth, 64);
     resetDataLayout("e-i64:64-v16:16-v24:32-v32:32-v48:64-"
                     "v96:128-v192:256-v256:256-v512:512-v1024:1024-G1");
   }

clang/test/CodeGenOpenCL/scoped-atomic.cl

@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 %s -cl-std=CL2.0 -emit-llvm -o - -triple spir-unknown-unknown -verify
+// RUN: %clang_cc1 %s -cl-std=CL2.0 -emit-llvm -o - -triple spir64-unknown-unknown -verify
+
+// expected-no-diagnostics
+
+int fi1a(int *i) {
+  int v;
+  __scoped_atomic_load(i, &v, __ATOMIC_RELAXED, __MEMORY_SCOPE_DEVICE);
+  return v;
+}
+
+#ifdef __SPIR64__
+long fl1a(long *i) {
+  long v;
+  __scoped_atomic_load(i, &v, __ATOMIC_RELAXED, __MEMORY_SCOPE_DEVICE);
+  return v;
+}
+#endif