564d85e090
In LLVM IR, `AlignmentBitfieldElementT` is 5-bit wide But that means that the maximal alignment exponent is `(1<<5)-2`, which is `30`, not `29`. And indeed, alignment of `1073741824` roundtrips IR serialization-deserialization. While this doesn't seem all that important, this doubles the maximal supported alignment from 512MiB to 1GiB, and there's actually one noticeable use-case for that; On X86, the huge pages can have sizes of 2MiB and 1GiB (!). So while this doesn't add support for truly huge alignments, which i think we can easily-ish do if wanted, i think this adds zero-cost support for a not-trivially-dismissable case. I don't believe we need any upgrade infrastructure, and since we don't explicitly record the IR version, we don't need to bump one either. As @craig.topper speculates in D108661#2963519, this might be an artificial limit imposed by the original implementation of the `getAlignment()` functions. Differential Revision: https://reviews.llvm.org/D108661
37 lines
3.6 KiB
C++
37 lines
3.6 KiB
C++
// RUN: %clang_cc1 -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s
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// RUN: %clang_cc1 -fsanitize=alignment -fno-sanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-NORECOVER,CHECK-SANITIZE-UNREACHABLE
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// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-recover=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-ANYRECOVER,CHECK-SANITIZE-RECOVER
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// RUN: %clang_cc1 -fsanitize=alignment -fsanitize-trap=alignment -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s -implicit-check-not="call void @__ubsan_handle_alignment_assumption" --check-prefixes=CHECK,CHECK-SANITIZE,CHECK-SANITIZE-TRAP,CHECK-SANITIZE-UNREACHABLE
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// CHECK-SANITIZE-ANYRECOVER: @[[CHAR:.*]] = {{.*}} c"'char **'\00" }
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// CHECK-SANITIZE-ANYRECOVER: @[[LINE_100_ALIGNMENT_ASSUMPTION:.*]] = {{.*}}, i32 100, i32 35 }, {{.*}}* @[[CHAR]] }
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void *caller(char **x, unsigned long offset) {
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// CHECK: define{{.*}} i8* @{{.*}}(i8** %[[X:.*]], i64 %[[OFFSET:.*]])
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// CHECK-NEXT: entry:
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// CHECK-NEXT: %[[X_ADDR:.*]] = alloca i8**, align 8
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// CHECK-NEXT: %[[OFFSET_ADDR:.*]] = alloca i64, align 8
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// CHECK-NEXT: store i8** %[[X]], i8*** %[[X_ADDR]], align 8
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// CHECK-NEXT: store i64 %[[OFFSET]], i64* %[[OFFSET_ADDR]], align 8
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// CHECK-NEXT: %[[X_RELOADED:.*]] = load i8**, i8*** %[[X_ADDR]], align 8
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// CHECK-NEXT: %[[BITCAST:.*]] = bitcast i8** %[[X_RELOADED]] to i8*
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// CHECK-NEXT: %[[OFFSET_RELOADED:.*]] = load i64, i64* %[[OFFSET_ADDR]], align 8
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// CHECK-SANITIZE-NEXT: %[[PTRINT:.*]] = ptrtoint i8* %[[BITCAST]] to i64
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// CHECK-SANITIZE-NEXT: %[[OFFSETPTR:.*]] = sub i64 %[[PTRINT]], %[[OFFSET_RELOADED]]
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// CHECK-SANITIZE-NEXT: %[[MASKEDPTR:.*]] = and i64 %[[OFFSETPTR]], 1073741823
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// CHECK-SANITIZE-NEXT: %[[MASKCOND:.*]] = icmp eq i64 %[[MASKEDPTR]], 0
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// CHECK-SANITIZE-NEXT: %[[PTRINT_DUP:.*]] = ptrtoint i8* %[[BITCAST]] to i64, !nosanitize
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// CHECK-SANITIZE-NEXT: br i1 %[[MASKCOND]], label %[[CONT:.*]], label %[[HANDLER_ALIGNMENT_ASSUMPTION:[^,]+]],{{.*}} !nosanitize
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// CHECK-SANITIZE: [[HANDLER_ALIGNMENT_ASSUMPTION]]:
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// CHECK-SANITIZE-NORECOVER-NEXT: call void @__ubsan_handle_alignment_assumption_abort(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 1073741824, i64 %[[OFFSET_RELOADED]]){{.*}}, !nosanitize
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// CHECK-SANITIZE-RECOVER-NEXT: call void @__ubsan_handle_alignment_assumption(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 1073741824, i64 %[[OFFSET_RELOADED]]){{.*}}, !nosanitize
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// CHECK-SANITIZE-TRAP-NEXT: call void @llvm.ubsantrap(i8 23){{.*}}, !nosanitize
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// CHECK-SANITIZE-UNREACHABLE-NEXT: unreachable, !nosanitize
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// CHECK-SANITIZE: [[CONT]]:
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// CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(i8* %[[BITCAST]], i64 1073741824, i64 %[[OFFSET_RELOADED]]) ]
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// CHECK-NEXT: ret i8* %[[BITCAST]]
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// CHECK-NEXT: }
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#line 100
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return __builtin_assume_aligned(x, 0x80000000, offset);
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}
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