[PATCH] D59446: CodeGen: Preserve packed attribute in constStructWithPadding.

Peter Collingbourne via Phabricator via cfe-commits Fri, 15 Mar 2019 20:45:48 -0700

pcc created this revision.
pcc added reviewers: jfb, glider.
Herald added a project: clang.


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


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D59446

Files:
  clang/lib/CodeGen/CGDecl.cpp
  clang/test/CodeGenCXX/auto-var-init.cpp


Index: clang/test/CodeGenCXX/auto-var-init.cpp
===================================================================
--- clang/test/CodeGenCXX/auto-var-init.cpp
+++ clang/test/CodeGenCXX/auto-var-init.cpp
@@ -85,6 +85,8 @@
 // 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
@@ -778,6 +780,10 @@
 // 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
Index: clang/lib/CodeGen/CGDecl.cpp
===================================================================
--- clang/lib/CodeGen/CGDecl.cpp
+++ clang/lib/CodeGen/CGDecl.cpp
@@ -1113,7 +1113,7 @@
   }
   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

Index: clang/test/CodeGenCXX/auto-var-init.cpp
===================================================================
--- clang/test/CodeGenCXX/auto-var-init.cpp
+++ clang/test/CodeGenCXX/auto-var-init.cpp
@@ -85,6 +85,8 @@
 // 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
@@ -778,6 +780,10 @@
 // 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
Index: clang/lib/CodeGen/CGDecl.cpp
===================================================================
--- clang/lib/CodeGen/CGDecl.cpp
+++ clang/lib/CodeGen/CGDecl.cpp
@@ -1113,7 +1113,7 @@
   }
   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

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[PATCH] D59446: CodeGen: Preserve packed attribute in constStructWithPadding.

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