From 83497d9eadd04a0ee57e4858a8f3b7b3cb99a22b Mon Sep 17 00:00:00 2001 From: Richard Smith Date: Thu, 19 Jul 2018 21:38:56 +0000 Subject: [PATCH] When we choose to use zeroinitializer for a trailing portion of an array constant, don't convert the rest into a packed struct. If an array constant has a large non-zero portion and a large zero portion, we want to emit the first part as an array and the rest as a zeroinitializer if possible. This fixes a memory usage regression from r333141 when compiling PHP. llvm-svn: 337498 --- clang/lib/CodeGen/CGExprConstant.cpp | 14 +++++++++++++- clang/test/CodeGen/init.c | 4 ++++ 2 files changed, 17 insertions(+), 1 deletion(-) diff --git a/clang/lib/CodeGen/CGExprConstant.cpp b/clang/lib/CodeGen/CGExprConstant.cpp index b26ff3d..afe2bfe 100644 --- a/clang/lib/CodeGen/CGExprConstant.cpp +++ b/clang/lib/CodeGen/CGExprConstant.cpp @@ -659,7 +659,19 @@ EmitArrayConstant(CodeGenModule &CGM, const ConstantArrayType *DestType, if (TrailingZeroes >= 8) { assert(Elements.size() >= NonzeroLength && "missing initializer for non-zero element"); - Elements.resize(NonzeroLength + 1); + + // If all the elements had the same type up to the trailing zeroes, emit a + // struct of two arrays (the nonzero data and the zeroinitializer). + if (CommonElementType && NonzeroLength >= 8) { + llvm::Constant *Initial = llvm::ConstantArray::get( + llvm::ArrayType::get(CommonElementType, ArrayBound), + makeArrayRef(Elements).take_front(NonzeroLength)); + Elements.resize(2); + Elements[0] = Initial; + } else { + Elements.resize(NonzeroLength + 1); + } + auto *FillerType = CommonElementType ? CommonElementType diff --git a/clang/test/CodeGen/init.c b/clang/test/CodeGen/init.c index b539681..770995f 100644 --- a/clang/test/CodeGen/init.c +++ b/clang/test/CodeGen/init.c @@ -81,6 +81,10 @@ struct Huge { int arr[1000 * 1000 * 1000]; } huge_struct = {1, {2, 0, 0, 0}}; +// CHECK-DAG: @large_array_with_zeroes = constant <{ [21 x i8], [979 x i8] }> <{ [21 x i8] c"abc\01\02\03xyzzy\00\00\00\00\00\00\00\00\00q", [979 x i8] zeroinitializer }> +const char large_array_with_zeroes[1000] = { + 'a', 'b', 'c', 1, 2, 3, 'x', 'y', 'z', 'z', 'y', [20] = 'q' +}; // PR279 comment #3 char test8(int X) { -- 2.7.4