CodeGen: Preserve packed attribute in constStructWithPadding.

[pcc]

Summary

Otherwise the object may have an incorrect size due to tail padding.

[jfb]

Nice catch!

clang/lib/CodeGen/CGDecl.cpp

static llvm::Constant *constStructWithPadding(CodeGenModule &CGM,
   }
   unsigned TotalSize = Layout->getSizeInBytes();
   if (SizeSoFar < TotalSize) {
     auto *PadTy = llvm::ArrayType::get(Int8Ty, TotalSize - SizeSoFar);
     Values.push_back(patternOrZeroFor(CGM, isPattern, PadTy));
   }
   if (NestedIntact && Values.size() == STy->getNumElements())
     return constant;
-  return llvm::ConstantStruct::getAnon(Values);
+  return llvm::ConstantStruct::getAnon(Values, STy->isPacked());
 }
 
 /// Replace all padding bytes in a given constant with either a pattern byte or
 /// 0x00.
 static llvm::Constant *constWithPadding(CodeGenModule &CGM, IsPattern isPattern,
                                         llvm::Constant *constant) {
   llvm::Type *OrigTy = constant->getType();
   if (const auto STy = dyn_cast<llvm::StructType>(OrigTy))

clang/test/CodeGenCXX/auto-var-init.cpp

 // PATTERN-O0: @__const.test_paddedpacked_uninit.uninit = private unnamed_addr constant %struct.paddedpacked <{ i8 -86, i32 -1431655766 }>, align 1
 // PATTERN: @__const.test_paddedpacked_custom.custom = private unnamed_addr constant %struct.paddedpacked <{ i8 42, i32 13371337 }>, align 1
 // ZERO: @__const.test_paddedpacked_custom.custom = private unnamed_addr constant %struct.paddedpacked <{ i8 42, i32 13371337 }>, align 1
 struct paddedpacked { char c; int i; } __attribute__((packed));
 // PATTERN-O0: @__const.test_paddedpackedarray_uninit.uninit = private unnamed_addr constant %struct.paddedpackedarray { [2 x %struct.paddedpacked] [%struct.paddedpacked <{ i8 -86, i32 -1431655766 }>, %struct.paddedpacked <{ i8 -86, i32 -1431655766 }>] }, align 1
 // PATTERN: @__const.test_paddedpackedarray_custom.custom = private unnamed_addr constant %struct.paddedpackedarray { [2 x %struct.paddedpacked] [%struct.paddedpacked <{ i8 42, i32 13371337 }>, %struct.paddedpacked <{ i8 43, i32 13371338 }>] }, align 1
 // ZERO: @__const.test_paddedpackedarray_custom.custom = private unnamed_addr constant %struct.paddedpackedarray { [2 x %struct.paddedpacked] [%struct.paddedpacked <{ i8 42, i32 13371337 }>, %struct.paddedpacked <{ i8 43, i32 13371338 }>] }, align 1
 struct paddedpackedarray { struct paddedpacked p[2]; };
+// PATTERN-O0: @__const.test_unpackedinpacked_uninit.uninit = private unnamed_addr constant <{ { i8, [3 x i8], i32 }, i8 }> <{ { i8, [3 x i8], i32 } { i8 -86, [3 x i8] c"\AA\AA\AA", i32 -1431655766 }, i8 -86 }>, align 1
+struct unpackedinpacked { padded a; char b; } __attribute__((packed));
 // PATTERN-O0: @__const.test_paddednested_uninit.uninit = private unnamed_addr constant { { i8, [3 x i8], i32 }, { i8, [3 x i8], i32 } } { { i8, [3 x i8], i32 } { i8 -86, [3 x i8] c"\AA\AA\AA", i32 -1431655766 }, { i8, [3 x i8], i32 } { i8 -86, [3 x i8] c"\AA\AA\AA", i32 -1431655766 } }, align 4
 // PATTERN: @__const.test_paddednested_custom.custom = private unnamed_addr constant { { i8, [3 x i8], i32 }, { i8, [3 x i8], i32 } } { { i8, [3 x i8], i32 } { i8 42, [3 x i8] c"\AA\AA\AA", i32 13371337 }, { i8, [3 x i8], i32 } { i8 43, [3 x i8] c"\AA\AA\AA", i32 13371338 } }, align 4
 // ZERO: @__const.test_paddednested_custom.custom = private unnamed_addr constant { { i8, [3 x i8], i32 }, { i8, [3 x i8], i32 } } { { i8, [3 x i8], i32 } { i8 42, [3 x i8] zeroinitializer, i32 13371337 }, { i8, [3 x i8], i32 } { i8 43, [3 x i8] zeroinitializer, i32 13371338 } }, align 4
 struct paddednested { struct padded p1, p2; };
 // PATTERN-O0: @__const.test_paddedpackednested_uninit.uninit = private unnamed_addr constant %struct.paddedpackednested { %struct.paddedpacked <{ i8 -86, i32 -1431655766 }>, %struct.paddedpacked <{ i8 -86, i32 -1431655766 }> }, align 1
 // PATTERN: @__const.test_paddedpackednested_custom.custom = private unnamed_addr constant %struct.paddedpackednested { %struct.paddedpacked <{ i8 42, i32 13371337 }>, %struct.paddedpacked <{ i8 43, i32 13371338 }> }, align 1
 // ZERO: @__const.test_paddedpackednested_custom.custom = private unnamed_addr constant %struct.paddedpackednested { %struct.paddedpacked <{ i8 42, i32 13371337 }>, %struct.paddedpacked <{ i8 43, i32 13371338 }> }, align 1
 struct paddedpackednested { struct paddedpacked p1, p2; };

 
 TEST_CUSTOM(paddedpackedarray, paddedpackedarray, { {{ 42, 13371337 }, { 43, 13371338 }} });
 // CHECK-LABEL: @test_paddedpackedarray_custom()
 // CHECK:       %custom = alloca %struct.paddedpackedarray, align
 // CHECK-NEXT:  bitcast
 // CHECK-NEXT:  call void @llvm.memcpy{{.*}}({{.*}}@__const.test_paddedpackedarray_custom.custom
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%custom)
 
+TEST_UNINIT(unpackedinpacked, unpackedinpacked);
+// CHECK-LABEL: @test_unpackedinpacked_uninit()
+// PATTERN-O0:  call void @llvm.memcpy{{.*}}, i64 9, i1 false)
+
 TEST_UNINIT(paddednested, paddednested);
 // CHECK-LABEL: @test_paddednested_uninit()
 // CHECK:       %uninit = alloca %struct.paddednested, align
 // CHECK-NEXT:  call void @{{.*}}used{{.*}}%uninit)
 // PATTERN-LABEL: @test_paddednested_uninit()
 // PATTERN-O0: call void @llvm.memcpy{{.*}} @__const.test_paddednested_uninit.uninit
 // PATTERN-O1: getelementptr
 // PATTERN-O1: call void @llvm.memset{{.*}}({{.*}}, i8 -86, i64 16