forked from OSchip/llvm-project
Introduce f[no-]max-unknown-pointer-align=[number] option
to instruct the code generator to not enforce a higher alignment than the given number (of bytes) when accessing memory via an opaque pointer or reference. Patch reviewed by John McCall (with post-commit review pending). rdar://16254558 llvm-svn: 214911
This commit is contained in:
Fariborz Jahanian
parent
4e4cb6bc30
commit
bcd82afad6
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@ -1111,6 +1111,37 @@ are listed below.
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This option restricts the generated code to use general registers
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only. This only applies to the AArch64 architecture.
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**-f[no-]max-unknown-pointer-align=[number]**
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Instruct the code generator to not enforce a higher alignment than the given
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number (of bytes) when accessing memory via an opaque pointer or reference.
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This cap is ignored when directly accessing a variable or when the pointee
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type has an explicit “aligned” attribute.
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The value should usually be determined by the properties of the system allocator.
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Some builtin types, especially vector types, have very high natural alignments;
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when working with values of those types, Clang usually wants to use instructions
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that take advantage of that alignment. However, many system allocators do
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not promise to return memory that is more than 8-byte or 16-byte-aligned. Use
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this option to limit the alignment that the compiler can assume for an arbitrary
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pointer, which may point onto the heap.
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This option does not affect the ABI alignment of types; the layout of structs and
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unions and the value returned by the alignof operator remain the same.
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This option can be overridden on a case-by-case basis by putting an explicit
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“aligned” alignment on a struct, union, or typedef. For example:
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.. code-block:: console
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#include <immintrin.h>
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// Make an aligned typedef of the AVX-512 16-int vector type.
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typedef __v16si __aligned_v16si __attribute__((aligned(64)));
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void initialize_vector(__aligned_v16si *v) {
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// The compiler may assume that ‘v’ is 64-byte aligned, regardless of the
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// value of -fmax-unknown-pointer-align.
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}
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Profile Guided Optimization
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---------------------------
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@ -106,6 +106,8 @@ LANGOPT(OptimizeSize , 1, 0, "__OPTIMIZE_SIZE__ predefined macro")
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LANGOPT(Static , 1, 0, "__STATIC__ predefined macro (as opposed to __DYNAMIC__)")
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VALUE_LANGOPT(PackStruct , 32, 0,
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"default struct packing maximum alignment")
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VALUE_LANGOPT(MaxTypeAlign , 32, 0,
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"default maximum alignment for types")
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VALUE_LANGOPT(PICLevel , 2, 0, "__PIC__ level")
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VALUE_LANGOPT(PIELevel , 2, 0, "__PIE__ level")
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LANGOPT(GNUInline , 1, 0, "GNU inline semantics")
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@ -804,6 +804,9 @@ def fpack_struct : Flag<["-"], "fpack-struct">, Group<f_Group>;
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def fno_pack_struct : Flag<["-"], "fno-pack-struct">, Group<f_Group>;
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def fpack_struct_EQ : Joined<["-"], "fpack-struct=">, Group<f_Group>, Flags<[CC1Option]>,
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HelpText<"Specify the default maximum struct packing alignment">;
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def fmax_type_align_EQ : Joined<["-"], "fmax-type-align=">, Group<f_Group>, Flags<[CC1Option]>,
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HelpText<"Specify the maximum alignment to enforce on pointers lacking an explicit alignment">;
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def fno_max_type_align : Flag<["-"], "fno-max-type-align">, Group<f_Group>;
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def fpascal_strings : Flag<["-"], "fpascal-strings">, Group<f_Group>, Flags<[CC1Option]>,
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HelpText<"Recognize and construct Pascal-style string literals">;
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def fpcc_struct_return : Flag<["-"], "fpcc-struct-return">, Group<f_Group>, Flags<[CC1Option]>,
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@ -1399,8 +1399,13 @@ public:
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LValue MakeNaturalAlignAddrLValue(llvm::Value *V, QualType T) {
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CharUnits Alignment;
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if (!T->isIncompleteType())
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if (!T->isIncompleteType()) {
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Alignment = getContext().getTypeAlignInChars(T);
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unsigned MaxAlign = getContext().getLangOpts().MaxTypeAlign;
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if (MaxAlign && Alignment.getQuantity() > MaxAlign &&
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!getContext().isAlignmentRequired(T))
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Alignment = CharUnits::fromQuantity(MaxAlign);
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}
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return LValue::MakeAddr(V, T, Alignment, getContext(),
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CGM.getTBAAInfo(T));
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}
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@ -4134,6 +4134,21 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
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CmdArgs.push_back("-fpack-struct=1");
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}
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// Handle -fmax-type-align=N and -fno-type-align
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bool SkipMaxTypeAlign = Args.hasArg(options::OPT_fno_max_type_align);
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if (Arg *A = Args.getLastArg(options::OPT_fmax_type_align_EQ)) {
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if (!SkipMaxTypeAlign) {
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std::string MaxTypeAlignStr = "-fmax-type-align=";
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MaxTypeAlignStr += A->getValue();
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CmdArgs.push_back(Args.MakeArgString(MaxTypeAlignStr));
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}
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} else if (getToolChain().getTriple().isOSDarwin()) {
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if (!SkipMaxTypeAlign) {
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std::string MaxTypeAlignStr = "-fmax-type-align=16";
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CmdArgs.push_back(Args.MakeArgString(MaxTypeAlignStr));
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}
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}
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if (KernelOrKext || isNoCommonDefault(getToolChain().getTriple())) {
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if (!Args.hasArg(options::OPT_fcommon))
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CmdArgs.push_back("-fno-common");
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@ -1476,6 +1476,7 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
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Args.hasArg(OPT_fencode_extended_block_signature);
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Opts.EmitAllDecls = Args.hasArg(OPT_femit_all_decls);
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Opts.PackStruct = getLastArgIntValue(Args, OPT_fpack_struct_EQ, 0, Diags);
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Opts.MaxTypeAlign = getLastArgIntValue(Args, OPT_fmax_type_align_EQ, 0, Diags);
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Opts.PICLevel = getLastArgIntValue(Args, OPT_pic_level, 0, Diags);
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Opts.PIELevel = getLastArgIntValue(Args, OPT_pie_level, 0, Diags);
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Opts.Static = Args.hasArg(OPT_static_define);
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@ -0,0 +1,57 @@
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// RUN: %clang_cc1 -x c++ %s -O0 -triple=x86_64-apple-darwin -target-feature +avx2 -fmax-type-align=16 -emit-llvm -o - -Werror | FileCheck %s
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// rdar://16254558
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typedef float AVX2Float __attribute__((__vector_size__(32)));
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volatile float TestAlign(void)
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{
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volatile AVX2Float *p = new AVX2Float;
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*p = *p;
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AVX2Float r = *p;
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return r[0];
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}
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// CHECK: [[R:%.*]] = alloca <8 x float>, align 32
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// CHECK-NEXT: [[CALL:%.*]] = call noalias i8* @_Znwm(i64 32)
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// CHECK-NEXT: [[ZERO:%.*]] = bitcast i8* [[CALL]] to <8 x float>*
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// CHECK-NEXT: store <8 x float>* [[ZERO]], <8 x float>** [[P:%.*]], align 8
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// CHECK-NEXT: [[ONE:%.*]] = load <8 x float>** [[P]], align 8
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// CHECK-NEXT: [[TWO:%.*]] = load volatile <8 x float>* [[ONE]], align 16
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// CHECK-NEXT: [[THREE:%.*]] = load <8 x float>** [[P]], align 8
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// CHECK-NEXT: store volatile <8 x float> [[TWO]], <8 x float>* [[THREE]], align 16
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// CHECK-NEXT: [[FOUR:%.*]] = load <8 x float>** [[P]], align 8
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// CHECK-NEXT: [[FIVE:%.*]] = load volatile <8 x float>* [[FOUR]], align 16
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// CHECK-NEXT: store <8 x float> [[FIVE]], <8 x float>* [[R]], align 32
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// CHECK-NEXT: [[SIX:%.*]] = load <8 x float>* [[R]], align 32
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// CHECK-NEXT: [[VECEXT:%.*]] = extractelement <8 x float> [[SIX]], i32 0
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// CHECK-NEXT: ret float [[VECEXT]]
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typedef float AVX2Float_Explicitly_aligned __attribute__((__vector_size__(32))) __attribute__((aligned (32)));
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typedef AVX2Float_Explicitly_aligned AVX2Float_indirect;
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typedef AVX2Float_indirect AVX2Float_use_existing_align;
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volatile float TestAlign2(void)
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{
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volatile AVX2Float_use_existing_align *p = new AVX2Float_use_existing_align;
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*p = *p;
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AVX2Float_use_existing_align r = *p;
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return r[0];
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}
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// CHECK: [[R:%.*]] = alloca <8 x float>, align 32
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// CHECK-NEXT: [[CALL:%.*]] = call noalias i8* @_Znwm(i64 32)
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// CHECK-NEXT: [[ZERO:%.*]] = bitcast i8* [[CALL]] to <8 x float>*
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// CHECK-NEXT: store <8 x float>* [[ZERO]], <8 x float>** [[P:%.*]], align 8
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// CHECK-NEXT: [[ONE:%.*]] = load <8 x float>** [[P]], align 8
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// CHECK-NEXT: [[TWO:%.*]] = load volatile <8 x float>* [[ONE]], align 32
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// CHECK-NEXT: [[THREE:%.*]] = load <8 x float>** [[P]], align 8
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// CHECK-NEXT: store volatile <8 x float> [[TWO]], <8 x float>* [[THREE]], align 32
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// CHECK-NEXT: [[FOUR:%.*]] = load <8 x float>** [[P]], align 8
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// CHECK-NEXT: [[FIVE:%.*]] = load volatile <8 x float>* [[FOUR]], align 32
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// CHECK-NEXT: store <8 x float> [[FIVE]], <8 x float>* [[R]], align 32
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// CHECK-NEXT: [[SIX:%.*]] = load <8 x float>* [[R]], align 32
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// CHECK-NEXT: [[VECEXT:%.*]] = extractelement <8 x float> [[SIX]], i32 0
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// CHECK-NEXT: ret float [[VECEXT]]
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@ -0,0 +1,15 @@
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// Check the -fmax-type-align=N flag
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// rdar://16254558
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//
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// RUN: %clang -no-canonical-prefixes -target x86_64-apple-macosx10.7.0 %s -o - -### 2>&1 | \
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// RUN: FileCheck -check-prefix=TEST0 %s
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// TEST0: -fmax-type-align=16
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// RUN: %clang -no-canonical-prefixes -fmax-type-align=32 -target x86_64-apple-macosx10.7.0 %s -o - -### 2>&1 | \
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// RUN: FileCheck -check-prefix=TEST1 %s
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// TEST1: -fmax-type-align=32
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// RUN: %clang -no-canonical-prefixes -fmax-type-align=32 -fno-max-type-align -target x86_64-apple-macosx10.7.0 %s -o - -### 2>&1 | \
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// RUN: FileCheck -check-prefix=TEST2 %s
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// TEST2-NOT: -fmax-type-align
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// RUN: %clang -no-canonical-prefixes -fno-max-type-align -target x86_64-apple-macosx10.7.0 %s -o - -### 2>&1 | \
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// RUN: FileCheck -check-prefix=TEST3 %s
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// TEST3-NOT: -fmax-type-align
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@ -3,11 +3,11 @@
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// TEST0: clang{{.*}}" "-cc1"
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// TEST0: "-rewrite-objc"
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// FIXME: CHECK-NOT is broken somehow, it doesn't work here. Check adjacency instead.
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// TEST0: "-fmessage-length" "0" "-stack-protector" "1" "-mstackrealign" "-fblocks" "-fobjc-runtime=macosx-fragile" "-fencode-extended-block-signature" "-fno-objc-infer-related-result-type" "-fobjc-exceptions" "-fexceptions" "-fdiagnostics-show-option"
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// TEST0: "-fmessage-length" "0" "-stack-protector" "1" "-mstackrealign" "-fblocks" "-fobjc-runtime=macosx-fragile" "-fencode-extended-block-signature" "-fno-objc-infer-related-result-type" "-fobjc-exceptions" "-fexceptions" "-fmax-type-align=16" "-fdiagnostics-show-option"
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// TEST0: rewrite-legacy-objc.m"
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// RUN: %clang -no-canonical-prefixes -target i386-apple-macosx10.9.0 -rewrite-legacy-objc %s -o - -### 2>&1 | \
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// RUN: FileCheck -check-prefix=TEST1 %s
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// RUN: %clang -no-canonical-prefixes -target i386-apple-macosx10.6.0 -rewrite-legacy-objc %s -o - -### 2>&1 | \
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// RUN: FileCheck -check-prefix=TEST2 %s
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// TEST1: "-fmessage-length" "0" "-stack-protector" "1" "-mstackrealign" "-fblocks" "-fobjc-runtime=macosx-fragile" "-fobjc-subscripting-legacy-runtime" "-fencode-extended-block-signature" "-fno-objc-infer-related-result-type" "-fobjc-exceptions" "-fdiagnostics-show-option"
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// TEST2: "-fmessage-length" "0" "-stack-protector" "1" "-mstackrealign" "-fblocks" "-fobjc-runtime=macosx-fragile" "-fencode-extended-block-signature" "-fno-objc-infer-related-result-type" "-fobjc-exceptions" "-fdiagnostics-show-option"
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// TEST1: "-fmessage-length" "0" "-stack-protector" "1" "-mstackrealign" "-fblocks" "-fobjc-runtime=macosx-fragile" "-fobjc-subscripting-legacy-runtime" "-fencode-extended-block-signature" "-fno-objc-infer-related-result-type" "-fobjc-exceptions" "-fmax-type-align=16" "-fdiagnostics-show-option"
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// TEST2: "-fmessage-length" "0" "-stack-protector" "1" "-mstackrealign" "-fblocks" "-fobjc-runtime=macosx-fragile" "-fencode-extended-block-signature" "-fno-objc-infer-related-result-type" "-fobjc-exceptions" "-fmax-type-align=16" "-fdiagnostics-show-option"
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@ -3,4 +3,4 @@
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// TEST0: clang{{.*}}" "-cc1"
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// TEST0: "-rewrite-objc"
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// FIXME: CHECK-NOT is broken somehow, it doesn't work here. Check adjacency instead.
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// TEST0: "-fmessage-length" "0" "-stack-protector" "1" "-mstackrealign" "-fblocks" "-fobjc-runtime=macosx" "-fencode-extended-block-signature" "-fno-objc-infer-related-result-type" "-fobjc-exceptions" "-fexceptions" "-fdiagnostics-show-option"
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// TEST0: "-fmessage-length" "0" "-stack-protector" "1" "-mstackrealign" "-fblocks" "-fobjc-runtime=macosx" "-fencode-extended-block-signature" "-fno-objc-infer-related-result-type" "-fobjc-exceptions" "-fexceptions" "-fmax-type-align=16" "-fdiagnostics-show-option"
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