[hwasan] Consider order of mapping copts (#109621)

Flags "-hwasan-mapping-offset" and
"-hwasan-mapping-offset-dynamic" are mutually
exclusive, use the last one.

Author: vitalybuka

llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp

@@ -1937,14 +1937,18 @@ void HWAddressSanitizer::ShadowMapping::init(Triple &TargetTriple,
     // Fuchsia is always PIE, which means that the beginning of the address
     // space is always available.
     SetFixed(0);
-  } else if (ClMappingOffset.getNumOccurrences() > 0) {
-    SetFixed(ClMappingOffset);
   } else if (ClEnableKhwasan || InstrumentWithCalls) {
     SetFixed(0);
     WithFrameRecord = false;
-  } else if (ClMappingOffsetDynamic.getNumOccurrences() > 0) {
-    Kind = ClMappingOffsetDynamic;
   }
 
   WithFrameRecord = optOr(ClFrameRecords, WithFrameRecord);
+
+  // Apply the last of ClMappingOffset and ClMappingOffsetDynamic.
+  Kind = optOr(ClMappingOffsetDynamic, Kind);
+  if (ClMappingOffset.getNumOccurrences() > 0 &&
+      !(ClMappingOffsetDynamic.getNumOccurrences() > 0 &&
+        ClMappingOffsetDynamic.getPosition() > ClMappingOffset.getPosition())) {
+    SetFixed(ClMappingOffset);
+  }
 }

llvm/test/Instrumentation/HWAddressSanitizer/mapping-override.ll

@@ -0,0 +1,50 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
+
+; RUN: opt < %s -passes=hwasan -S | FileCheck %s
+; RUN: opt < %s -passes=hwasan -hwasan-mapping-offset-dynamic=global -S | FileCheck %s --check-prefixes=GLOBAL
+; RUN: opt < %s -passes=hwasan -hwasan-mapping-offset=567 -S | FileCheck %s --check-prefixes=FIXED
+; RUN: opt < %s -passes=hwasan -hwasan-mapping-offset=567 -hwasan-mapping-offset-dynamic=global -S | FileCheck %s --check-prefixes=FIXED-GLOBAL
+; RUN: opt < %s -passes=hwasan -hwasan-mapping-offset-dynamic=global -hwasan-mapping-offset=567 -S | FileCheck %s --check-prefixes=GLOBAL-FIXED
+
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64--linux-android"
+
+define i8 @test_load8(ptr %a) sanitize_hwaddress {
+; CHECK-LABEL: define i8 @test_load8
+; CHECK-SAME: (ptr [[A:%.*]]) #[[ATTR0:[0-9]+]] {
+; CHECK-NEXT:    [[DOTHWASAN_SHADOW:%.*]] = call ptr asm "", "=r,0"(ptr @__hwasan_shadow)
+; CHECK-NEXT:    call void @llvm.hwasan.check.memaccess(ptr [[DOTHWASAN_SHADOW]], ptr [[A]], i32 0)
+; CHECK-NEXT:    [[B:%.*]] = load i8, ptr [[A]], align 4
+; CHECK-NEXT:    ret i8 [[B]]
+;
+; GLOBAL-LABEL: define i8 @test_load8
+; GLOBAL-SAME: (ptr [[A:%.*]]) #[[ATTR0:[0-9]+]] {
+; GLOBAL-NEXT:    [[TMP1:%.*]] = load ptr, ptr @__hwasan_shadow_memory_dynamic_address, align 8
+; GLOBAL-NEXT:    call void @llvm.hwasan.check.memaccess(ptr [[TMP1]], ptr [[A]], i32 0)
+; GLOBAL-NEXT:    [[B:%.*]] = load i8, ptr [[A]], align 4
+; GLOBAL-NEXT:    ret i8 [[B]]
+;
+; FIXED-LABEL: define i8 @test_load8
+; FIXED-SAME: (ptr [[A:%.*]]) #[[ATTR0:[0-9]+]] {
+; FIXED-NEXT:    [[DOTHWASAN_SHADOW:%.*]] = call ptr asm "", "=r,0"(ptr inttoptr (i64 567 to ptr))
+; FIXED-NEXT:    call void @llvm.hwasan.check.memaccess(ptr [[DOTHWASAN_SHADOW]], ptr [[A]], i32 0)
+; FIXED-NEXT:    [[B:%.*]] = load i8, ptr [[A]], align 4
+; FIXED-NEXT:    ret i8 [[B]]
+;
+; FIXED-GLOBAL-LABEL: define i8 @test_load8
+; FIXED-GLOBAL-SAME: (ptr [[A:%.*]]) #[[ATTR0:[0-9]+]] {
+; FIXED-GLOBAL-NEXT:    [[TMP1:%.*]] = load ptr, ptr @__hwasan_shadow_memory_dynamic_address, align 8
+; FIXED-GLOBAL-NEXT:    call void @llvm.hwasan.check.memaccess(ptr [[TMP1]], ptr [[A]], i32 0)
+; FIXED-GLOBAL-NEXT:    [[B:%.*]] = load i8, ptr [[A]], align 4
+; FIXED-GLOBAL-NEXT:    ret i8 [[B]]
+;
+; GLOBAL-FIXED-LABEL: define i8 @test_load8
+; GLOBAL-FIXED-SAME: (ptr [[A:%.*]]) #[[ATTR0:[0-9]+]] {
+; GLOBAL-FIXED-NEXT:    [[DOTHWASAN_SHADOW:%.*]] = call ptr asm "", "=r,0"(ptr inttoptr (i64 567 to ptr))
+; GLOBAL-FIXED-NEXT:    call void @llvm.hwasan.check.memaccess(ptr [[DOTHWASAN_SHADOW]], ptr [[A]], i32 0)
+; GLOBAL-FIXED-NEXT:    [[B:%.*]] = load i8, ptr [[A]], align 4
+; GLOBAL-FIXED-NEXT:    ret i8 [[B]]
+;
+  %b = load i8, ptr %a, align 4
+  ret i8 %b
+}