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c1cfa1757c
When emitting TBAA information for enums in C code we currently just treat the data as an 'omnipotent char'. However, with C strict aliasing this means we fail to optimise certain cases. For example, in the SPEC2017 xz benchmark there are structs that contain arrays of enums, and clang pessmistically assumes that accesses to those enums could alias with other struct members that have a different type. According to https://en.cppreference.com/w/c/language/enum enums should be treated as 'int' types unless explicitly specified (C23) or if 'int' would not be large enough to hold all the enumerated values. In the latter case the compiler is free to choose a suitable integer that would hold all such values. When compiling C code this patch generates TBAA information for the enum by using an equivalent integer of the size clang has already chosen for the enum. I have ignored C++ for now because the rules are more complex. New test added here: clang/test/CodeGen/tbaa.c
117 lines
4.4 KiB
C
117 lines
4.4 KiB
C
// RUN: %clang_cc1 -triple x86_64-apple-darwin -O1 -no-struct-path-tbaa -disable-llvm-passes %s -emit-llvm -o - | FileCheck %s
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// RUN: %clang_cc1 -triple x86_64-apple-darwin -O1 -disable-llvm-passes %s -emit-llvm -o - | FileCheck %s -check-prefixes=PATH
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// RUN: %clang_cc1 -triple x86_64-apple-darwin -O0 -disable-llvm-passes %s -emit-llvm -o - | FileCheck %s -check-prefix=NO-TBAA
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// RUN: %clang_cc1 -triple x86_64-apple-darwin -O1 -relaxed-aliasing -disable-llvm-passes %s -emit-llvm -o - | FileCheck %s -check-prefix=NO-TBAA
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// Test TBAA metadata generated by front-end.
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//
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// NO-TBAA-NOT: !tbaa
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typedef unsigned char uint8_t;
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typedef unsigned short uint16_t;
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typedef unsigned int uint32_t;
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typedef unsigned long long uint64_t;
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typedef enum {
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RED_AUTO_32,
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GREEN_AUTO_32,
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BLUE_AUTO_32
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} EnumAuto32;
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typedef enum {
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RED_AUTO_64,
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GREEN_AUTO_64,
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BLUE_AUTO_64 = 0x100000000ull
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} EnumAuto64;
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typedef enum : uint16_t {
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RED_16,
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GREEN_16,
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BLUE_16
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} Enum16;
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typedef enum : uint8_t {
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RED_8,
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GREEN_8,
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BLUE_8
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} Enum8;
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uint32_t g0(EnumAuto32 *E, uint32_t *val) {
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// CHECK-LABEL: define{{.*}} i32 @g0(
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// CHECK: store i32 5, ptr %{{.*}}, align 4, !tbaa [[TAG_i32:!.*]]
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// CHECK: store i32 0, ptr %{{.*}}, align 4, !tbaa [[TAG_i32]]
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// CHECK: load i32, ptr %{{.*}}, align 4, !tbaa [[TAG_i32]]
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// PATH-LABEL: define{{.*}} i32 @g0(
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// PATH: store i32 5, ptr %{{.*}}, align 4, !tbaa [[TAG_i32:!.*]]
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// PATH: store i32 0, ptr %{{.*}}, align 4, !tbaa [[TAG_i32]]
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// PATH: load i32, ptr %{{.*}}, align 4, !tbaa [[TAG_i32]]
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*val = 5;
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*E = RED_AUTO_32;
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return *val;
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}
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uint64_t g1(EnumAuto64 *E, uint64_t *val) {
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// CHECK-LABEL: define{{.*}} i64 @g1(
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// CHECK: store i64 5, ptr %{{.*}}, align 8, !tbaa [[TAG_i64:!.*]]
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// CHECK: store i64 0, ptr %{{.*}}, align 8, !tbaa [[TAG_long:!.*]]
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// CHECK: load i64, ptr %{{.*}}, align 8, !tbaa [[TAG_i64]]
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// PATH-LABEL: define{{.*}} i64 @g1(
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// PATH: store i64 5, ptr %{{.*}}, align 8, !tbaa [[TAG_i64:!.*]]
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// PATH: store i64 0, ptr %{{.*}}, align 8, !tbaa [[TAG_long:!.*]]
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// PATH: load i64, ptr %{{.*}}, align 8, !tbaa [[TAG_i64]]
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*val = 5;
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*E = RED_AUTO_64;
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return *val;
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}
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uint16_t g2(Enum16 *E, uint16_t *val) {
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// CHECK-LABEL: define{{.*}} i16 @g2(
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// CHECK: store i16 5, ptr %{{.*}}, align 2, !tbaa [[TAG_i16:!.*]]
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// CHECK: store i16 0, ptr %{{.*}}, align 2, !tbaa [[TAG_i16]]
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// CHECK: load i16, ptr %{{.*}}, align 2, !tbaa [[TAG_i16]]
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// PATH-LABEL: define{{.*}} i16 @g2(
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// PATH: store i16 5, ptr %{{.*}}, align 2, !tbaa [[TAG_i16:!.*]]
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// PATH: store i16 0, ptr %{{.*}}, align 2, !tbaa [[TAG_i16]]
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// PATH: load i16, ptr %{{.*}}, align 2, !tbaa [[TAG_i16]]
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*val = 5;
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*E = RED_16;
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return *val;
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}
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uint8_t g3(Enum8 *E, uint8_t *val) {
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// CHECK-LABEL: define{{.*}} i8 @g3(
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// CHECK: store i8 5, ptr %{{.*}}, align 1, !tbaa [[TAG_i8:!.*]]
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// CHECK: store i8 0, ptr %{{.*}}, align 1, !tbaa [[TAG_i8]]
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// CHECK: load i8, ptr %{{.*}}, align 1, !tbaa [[TAG_i8]]
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// PATH-LABEL: define{{.*}} i8 @g3(
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// PATH: store i8 5, ptr %{{.*}}, align 1, !tbaa [[TAG_i8:!.*]]
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// PATH: store i8 0, ptr %{{.*}}, align 1, !tbaa [[TAG_i8]]
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// PATH: load i8, ptr %{{.*}}, align 1, !tbaa [[TAG_i8]]
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*val = 5;
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*E = RED_8;
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return *val;
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}
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// CHECK: [[TYPE_char:!.*]] = !{!"omnipotent char", [[TAG_c_tbaa:!.*]],
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// CHECK: [[TAG_c_tbaa]] = !{!"Simple C/C++ TBAA"}
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// CHECK: [[TAG_i32]] = !{[[TYPE_i32:!.*]], [[TYPE_i32]], i64 0}
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// CHECK: [[TYPE_i32]] = !{!"int", [[TYPE_char]],
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// CHECK: [[TAG_i64]] = !{[[TYPE_i64:!.*]], [[TYPE_i64]], i64 0}
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// CHECK: [[TYPE_i64]] = !{!"long long", [[TYPE_char]],
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// CHECK: [[TAG_long]] = !{[[TYPE_long:!.*]], [[TYPE_long]], i64 0}
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// CHECK: [[TYPE_long]] = !{!"long", [[TYPE_char]],
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// CHECK: [[TAG_i16]] = !{[[TYPE_i16:!.*]], [[TYPE_i16]], i64 0}
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// CHECK: [[TYPE_i16]] = !{!"short", [[TYPE_char]],
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// CHECK: [[TAG_i8]] = !{[[TYPE_i8:!.*]], [[TYPE_char]], i64 0}
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// PATH: [[TYPE_char:!.*]] = !{!"omnipotent char", [[TAG_c_tbaa:!.*]],
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// PATH: [[TAG_c_tbaa]] = !{!"Simple C/C++ TBAA"}
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// PATH: [[TAG_i32]] = !{[[TYPE_i32:!.*]], [[TYPE_i32]], i64 0}
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// PATH: [[TYPE_i32]] = !{!"int", [[TYPE_char]],
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// PATH: [[TAG_i64]] = !{[[TYPE_i64:!.*]], [[TYPE_i64]], i64 0}
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// PATH: [[TYPE_i64]] = !{!"long long", [[TYPE_char]],
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// PATH: [[TAG_long]] = !{[[TYPE_long:!.*]], [[TYPE_long]], i64 0}
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// PATH: [[TYPE_long]] = !{!"long", [[TYPE_char]],
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// PATH: [[TAG_i16]] = !{[[TYPE_i16:!.*]], [[TYPE_i16]], i64 0}
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// PATH: [[TYPE_i16]] = !{!"short", [[TYPE_char]],
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// PATH: [[TAG_i8]] = !{[[TYPE_i8:!.*]], [[TYPE_char]], i64 0}
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