[IRGen] Use 32-bit string hash for type id.

Use all 32 bits of malloc_type_descriptor_t's hash.

Author: nate-chandler

lib/IRGen/GenPointerAuth.cpp

@@ -327,8 +327,9 @@ PointerAuthInfo::getOtherDiscriminator(IRGenModule &IGM,
 
 static llvm::ConstantInt *getDiscriminatorForString(IRGenModule &IGM,
                                                     StringRef string) {
-  return llvm::ConstantInt::get(IGM.Int64Ty,
-                                llvm::getPointerAuthStableSipHash(string));
+  uint64_t hash = llvm::getStableSipHash(string);
+  uint32_t hash32 = (hash % std::numeric_limits<uint32_t>::max()) + 1;
+  return llvm::ConstantInt::get(IGM.Int64Ty, hash32);
 }
 
 static std::string mangle(AssociatedTypeDecl *assocType) {

test/IRGen/yield_once_enable_emit_type_malloc_coro_frame.sil

@@ -11,8 +11,8 @@ sil @marker : $(Builtin.Int32) -> ()
 // CHECK-SAME:  [[CORO_ATTRIBUTES:#[0-9]+]]
 sil @test_simple : $@yield_once () -> () {
 entry:
-  // CHECK-32: [[ID:%.*]] = call token (i32, i32, ptr, ptr, ptr, ptr, ...) @llvm.coro.id.retcon.once(i32 [[BUFFER_SIZE]], i32 [[BUFFER_ALIGN:4]], ptr %0, ptr @"$sIetA_TC", ptr @__swift_coroFrameAllocStub, ptr @free, i64 38223)
-  // CHECK-64: [[ID:%.*]] = call token (i32, i32, ptr, ptr, ptr, ptr, ...) @llvm.coro.id.retcon.once(i32 [[BUFFER_SIZE]], i32 [[BUFFER_ALIGN:8]], ptr %0, ptr @"$sIetA_TC", ptr @__swift_coroFrameAllocStub, ptr @free, i64 38223)
+  // CHECK-32: [[ID:%.*]] = call token (i32, i32, ptr, ptr, ptr, ptr, ...) @llvm.coro.id.retcon.once(i32 [[BUFFER_SIZE]], i32 [[BUFFER_ALIGN:4]], ptr %0, ptr @"$sIetA_TC", ptr @__swift_coroFrameAllocStub, ptr @free, i64 121146903)
+  // CHECK-64: [[ID:%.*]] = call token (i32, i32, ptr, ptr, ptr, ptr, ...) @llvm.coro.id.retcon.once(i32 [[BUFFER_SIZE]], i32 [[BUFFER_ALIGN:8]], ptr %0, ptr @"$sIetA_TC", ptr @__swift_coroFrameAllocStub, ptr @free, i64 121146903)
   // CHECK-NEXT:    [[BEGIN:%.*]] = call ptr @llvm.coro.begin(token [[ID]], ptr null)
 
   // CHECK-NEXT:    call swiftcc void @marker(i32 1000)