33a92af1b2
This patch adds an off-by-default flag which, when enabled via `-mllvm -msan-poison-undef-vectors=true`, fixes a false negative in MSan (partially-undefined constant fixed-length vectors). It is currently off by default since, by fixing the false positive, code/tests that previously passed MSan may start failing. The default will be changed in a future patch. Prior to this patch, MSan computes that partially-undefined constant fixed-length vectors are fully initialized, which leads to false negatives; moreover, benign vector rewriting could theoretically flip MSan's shadow computation from initialized to uninitialized or vice-versa (*). `-msan-poison-undef-vectors=true` calculates the shadow precisely: for each element of the vector, the corresponding shadow is fully uninitialized if the element is undefined/poisoned, otherwise it is fully initialized. Updates the test from https://github.com/llvm/llvm-project/pull/143823 (*) For example: ``` %x = insertelement <2 x i64> <i64 0, i64 poison>, i64 42, i64 0 %y = insertelement <2 x i64> <i64 poison, i64 poison>, i64 42, i64 0 ``` %x and %y are equivalent but, prior to this patch, MSan incorrectly computes the shadow of %x as <0, 0> rather than <0, -1>.
104 lines
4.3 KiB
LLVM
104 lines
4.3 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
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; RUN: opt < %s -S -passes='msan' -msan-poison-undef-vectors=true 2>&1 | FileCheck %s --check-prefixes=CHECK,CHECK-PRECISE
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; RUN: opt < %s -S -passes='msan' -msan-poison-undef-vectors=false 2>&1 | FileCheck %s --check-prefixes=CHECK,CHECK-IMPRECISE
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;
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; Regression test case for computing shadows of partially poisoned vectors.
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; Partially poisoned structs and arrays are not correctly implemented.
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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define <2 x i64> @left_poison(ptr %add.ptr) sanitize_memory {
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; CHECK-LABEL: define <2 x i64> @left_poison(
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; CHECK-SAME: ptr [[ADD_PTR:%.*]]) #[[ATTR0:[0-9]+]] {
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; CHECK-NEXT: call void @llvm.donothing()
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; CHECK-PRECISE: store <2 x i64> <i64 -1, i64 0>, ptr @__msan_retval_tls, align 8
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; CHECK-IMPRECISE: store <2 x i64> zeroinitializer, ptr @__msan_retval_tls, align 8
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; CHECK-NEXT: ret <2 x i64> <i64 poison, i64 42>
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;
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ret <2 x i64> <i64 poison, i64 42>
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}
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define <2 x i64> @right_poison(ptr %add.ptr) sanitize_memory {
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; CHECK-LABEL: define <2 x i64> @right_poison(
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; CHECK-SAME: ptr [[ADD_PTR:%.*]]) #[[ATTR0]] {
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; CHECK-NEXT: call void @llvm.donothing()
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; CHECK-PRECISE: store <2 x i64> <i64 0, i64 -1>, ptr @__msan_retval_tls, align 8
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; CHECK-IMPRECISE: store <2 x i64> zeroinitializer, ptr @__msan_retval_tls, align 8
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; CHECK-NEXT: ret <2 x i64> <i64 42, i64 poison>
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;
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ret <2 x i64> <i64 42, i64 poison>
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}
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define <2 x i64> @full_poison(ptr %add.ptr) sanitize_memory {
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; CHECK-LABEL: define <2 x i64> @full_poison(
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; CHECK-SAME: ptr [[ADD_PTR:%.*]]) #[[ATTR0]] {
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; CHECK-NEXT: call void @llvm.donothing()
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; CHECK-NEXT: store <2 x i64> splat (i64 -1), ptr @__msan_retval_tls, align 8
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; CHECK-NEXT: ret <2 x i64> poison
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;
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ret <2 x i64> <i64 poison, i64 poison>
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}
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define <2 x i64> @no_poison_or_undef(ptr %add.ptr) sanitize_memory {
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; CHECK-LABEL: define <2 x i64> @no_poison_or_undef(
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; CHECK-SAME: ptr [[ADD_PTR:%.*]]) #[[ATTR0]] {
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; CHECK-NEXT: call void @llvm.donothing()
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; CHECK-NEXT: store <2 x i64> zeroinitializer, ptr @__msan_retval_tls, align 8
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; CHECK-NEXT: ret <2 x i64> splat (i64 42)
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;
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ret <2 x i64> <i64 42, i64 42>
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}
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define <2 x i64> @left_undef(ptr %add.ptr) sanitize_memory {
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; CHECK-LABEL: define <2 x i64> @left_undef(
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; CHECK-SAME: ptr [[ADD_PTR:%.*]]) #[[ATTR0]] {
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; CHECK-NEXT: call void @llvm.donothing()
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; CHECK-PRECISE: store <2 x i64> <i64 -1, i64 0>, ptr @__msan_retval_tls, align 8
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; CHECK-IMPRECISE: store <2 x i64> zeroinitializer, ptr @__msan_retval_tls, align 8
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; CHECK-NEXT: ret <2 x i64> <i64 undef, i64 42>
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;
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ret <2 x i64> <i64 undef, i64 42>
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}
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define <2 x i64> @right_undef(ptr %add.ptr) sanitize_memory {
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; CHECK-LABEL: define <2 x i64> @right_undef(
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; CHECK-SAME: ptr [[ADD_PTR:%.*]]) #[[ATTR0]] {
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; CHECK-NEXT: call void @llvm.donothing()
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; CHECK-PRECISE: store <2 x i64> <i64 0, i64 -1>, ptr @__msan_retval_tls, align 8
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; CHECK-IMPRECISE: store <2 x i64> zeroinitializer, ptr @__msan_retval_tls, align 8
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; CHECK-NEXT: ret <2 x i64> <i64 42, i64 undef>
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;
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ret <2 x i64> <i64 42, i64 undef>
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}
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define <2 x i64> @full_undef(ptr %add.ptr) sanitize_memory {
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; CHECK-LABEL: define <2 x i64> @full_undef(
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; CHECK-SAME: ptr [[ADD_PTR:%.*]]) #[[ATTR0]] {
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; CHECK-NEXT: call void @llvm.donothing()
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; CHECK-NEXT: store <2 x i64> splat (i64 -1), ptr @__msan_retval_tls, align 8
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; CHECK-NEXT: ret <2 x i64> undef
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;
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ret <2 x i64> <i64 undef, i64 undef>
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}
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define {i64, i64} @struct_left_undef() sanitize_memory {
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; CHECK-LABEL: define { i64, i64 } @struct_left_undef(
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; CHECK-SAME: ) #[[ATTR0]] {
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; CHECK-NEXT: call void @llvm.donothing()
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; CHECK-NEXT: store { i64, i64 } zeroinitializer, ptr @__msan_retval_tls, align 8
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; CHECK-NEXT: ret { i64, i64 } { i64 undef, i64 42 }
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;
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ret {i64, i64} { i64 undef, i64 42 }
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}
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define [2x i64] @array_right_undef() sanitize_memory {
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; CHECK-LABEL: define [2 x i64] @array_right_undef(
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; CHECK-SAME: ) #[[ATTR0]] {
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; CHECK-NEXT: call void @llvm.donothing()
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; CHECK-NEXT: store [2 x i64] zeroinitializer, ptr @__msan_retval_tls, align 8
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; CHECK-NEXT: ret [2 x i64] [i64 42, i64 undef]
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;
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ret [2x i64] [ i64 42, i64 undef ]
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}
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