[flang] [libcxx] [clang] [llvm] [lld] [libcxxabi] [lldb] [libc] [msan] Unpoison indirect outputs for userspace using llvm.memset.* (PR #79924)

[Fangrui Song via cfe-commits]

https://github.com/MaskRay updated https://github.com/llvm/llvm-project/pull/79924

>From 07043d27155ffd89e23b64c77a99880b2fa57e57 Mon Sep 17 00:00:00 2001
From: Fangrui Song <i at maskray.me>
Date: Mon, 29 Jan 2024 17:02:18 -0800
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
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Created using spr 1.3.4
---
 .../Instrumentation/MemorySanitizer.cpp          |  5 ++++-
 .../MemorySanitizer/msan_asm_conservative.ll     | 16 ++++++++--------
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index 2b697557d8a92..0806d7a5b1452 100644
--- a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -4559,9 +4559,12 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
     } else {
       // ElemTy, derived from elementtype(), does not encode the alignment of
       // the pointer. Conservatively assume that the shadow memory is unaligned.
+      // Avoid StoreInst as SizeVal may be large, expanding to many
+      // instructions.
       auto [ShadowPtr, _] =
           getShadowOriginPtrUserspace(Operand, IRB, IRB.getInt8Ty(), Align(1));
-      IRB.CreateAlignedStore(getCleanShadow(ElemTy), ShadowPtr, Align(1));
+      IRB.CreateMemSet(ShadowPtr, ConstantInt::getNullValue(IRB.getInt8Ty()),
+                       SizeVal, Align(1));
     }
   }
 
diff --git a/llvm/test/Instrumentation/MemorySanitizer/msan_asm_conservative.ll b/llvm/test/Instrumentation/MemorySanitizer/msan_asm_conservative.ll
index 894f76b9b8d32..86ca697ed9a4c 100644
--- a/llvm/test/Instrumentation/MemorySanitizer/msan_asm_conservative.ll
+++ b/llvm/test/Instrumentation/MemorySanitizer/msan_asm_conservative.ll
@@ -177,8 +177,8 @@ entry:
 }
 
 ; CHECK-LABEL: @f_2i_2o_mem
-; USER-CONS:  store i32 0, ptr inttoptr (i64 xor (i64 ptrtoint (ptr @id1 to i64), i64 87960930222080) to ptr), align 1
-; USER-CONS:  store i32 0, ptr inttoptr (i64 xor (i64 ptrtoint (ptr @id2 to i64), i64 87960930222080) to ptr), align 1
+; USER-CONS:  call void @llvm.memset.p0.i64(ptr align 1 inttoptr (i64 xor (i64 ptrtoint (ptr @id1 to i64), i64 87960930222080) to ptr), i8 0, i64 4, i1 false)
+; USER-CONS:  call void @llvm.memset.p0.i64(ptr align 1 inttoptr (i64 xor (i64 ptrtoint (ptr @id2 to i64), i64 87960930222080) to ptr), i8 0, i64 4, i1 false)
 ; CHECK-CONS: call void @__msan_instrument_asm_store({{.*}}@id1{{.*}}, i64 4)
 ; CHECK-CONS: call void @__msan_instrument_asm_store({{.*}}@id2{{.*}}, i64 4)
 ; CHECK: call void asm "", "=*m,=*m,*m,*m,~{dirflag},~{fpsr},~{flags}"(ptr elementtype(i32) @id1, ptr elementtype(i32) @id2, ptr elementtype(i32) @is1, ptr elementtype(i32) @is2)
@@ -196,7 +196,7 @@ entry:
 
 ; CHECK-LABEL: @f_1i_1o_memreg
 ; CHECK: [[IS1_F7:%.*]] = load i32, ptr @is1, align 4
-; USER-CONS:  store i32 0, ptr inttoptr (i64 xor (i64 ptrtoint (ptr @id1 to i64), i64 87960930222080) to ptr), align 1
+; USER-CONS:  call void @llvm.memset.p0.i64(ptr align 1 inttoptr (i64 xor (i64 ptrtoint (ptr @id1 to i64), i64 87960930222080) to ptr), i8 0, i64 4, i1 false)
 ; CHECK-CONS: call void @__msan_instrument_asm_store({{.*}}@id1{{.*}}, i64 4)
 ; CHECK: call void @__msan_warning
 ; CHECK: call i32 asm "", "=r,=*m,r,*m,~{dirflag},~{fpsr},~{flags}"(ptr elementtype(i32) @id1, i32 [[IS1_F7]], ptr elementtype(i32) @is1)
@@ -215,7 +215,7 @@ entry:
 }
 
 ; CHECK-LABEL: @f_3o_reg_mem_reg
-; USER-CONS:  store i32 0, ptr inttoptr (i64 xor (i64 ptrtoint (ptr @id2 to i64), i64 87960930222080) to ptr), align 1
+; USER-CONS:  call void @llvm.memset.p0.i64(ptr align 1 inttoptr (i64 xor (i64 ptrtoint (ptr @id2 to i64), i64 87960930222080) to ptr), i8 0, i64 4, i1 false)
 ; CHECK-CONS: call void @__msan_instrument_asm_store(ptr @id2, i64 4)
 ; CHECK: call { i32, i32 } asm "", "=r,=*m,=r,~{dirflag},~{fpsr},~{flags}"(ptr elementtype(i32) @id2)
 
@@ -240,7 +240,7 @@ entry:
 ; CHECK: [[PAIR1_F9:%.*]] = load {{.*}} @pair1
 ; CHECK: [[C1_F9:%.*]] = load {{.*}} @c1
 ; CHECK: [[MEMCPY_S1_F9:%.*]] = load {{.*}} @memcpy_s1
-; USER-CONS:  store { i32, i32 } zeroinitializer, ptr inttoptr (i64 xor (i64 ptrtoint (ptr @pair2 to i64), i64 87960930222080) to ptr), align 1
+; USER-CONS:  call void @llvm.memset.p0.i64(ptr align 1 inttoptr (i64 xor (i64 ptrtoint (ptr @pair2 to i64), i64 87960930222080) to ptr), i8 0, i64 8, i1 false)
 ; CHECK-CONS: call void @__msan_instrument_asm_store({{.*}}@pair2{{.*}}, i64 8)
 ; CHECK: call void @__msan_warning
 ; KMSAN: call void @__msan_warning
@@ -257,9 +257,9 @@ entry:
 }
 
 ; CHECK-LABEL: @f_3i_3o_complex_mem
-; USER-CONS:       store { i32, i32 } zeroinitializer, ptr inttoptr (i64 xor (i64 ptrtoint (ptr @pair2 to i64), i64 87960930222080) to ptr), align 1
-; USER-CONS-NEXT:  store i8 0, ptr inttoptr (i64 xor (i64 ptrtoint (ptr @c2 to i64), i64 87960930222080) to ptr), align 1
-; USER-CONS-NEXT:  store i64 0, ptr inttoptr (i64 xor (i64 ptrtoint (ptr @memcpy_d1 to i64), i64 87960930222080) to ptr), align 1
+; USER-CONS:       call void @llvm.memset.p0.i64(ptr align 1 inttoptr (i64 xor (i64 ptrtoint (ptr @pair2 to i64), i64 87960930222080) to ptr), i8 0, i64 8, i1 false)
+; USER-CONS-NEXT:  call void @llvm.memset.p0.i64(ptr align 1 inttoptr (i64 xor (i64 ptrtoint (ptr @c2 to i64), i64 87960930222080) to ptr), i8 0, i64 1, i1 false)
+; USER-CONS-NEXT:  call void @llvm.memset.p0.i64(ptr align 1 inttoptr (i64 xor (i64 ptrtoint (ptr @memcpy_d1 to i64), i64 87960930222080) to ptr), i8 0, i64 8, i1 false)
 ; CHECK-CONS:      call void @__msan_instrument_asm_store({{.*}}@pair2{{.*}}, i64 8)
 ; CHECK-CONS:      call void @__msan_instrument_asm_store({{.*}}@c2{{.*}}, i64 1)
 ; CHECK-CONS:      call void @__msan_instrument_asm_store({{.*}}@memcpy_d1{{.*}}, i64 8)