[compiler-rt] [win/asan] GetInstructionSize: Fix `41 81 7c ...` to return 9. (PR #117828)

[via llvm-commits]

https://github.com/bernhardu updated https://github.com/llvm/llvm-project/pull/117828

>From 5520453cea0c818de71353fe13f1f641ea503be6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bernhard=20=C3=9Cbelacker?= <bernhardu at mailbox.org>
Date: Sat, 30 Nov 2024 22:00:06 +0100
Subject: [PATCH] [win/asan] GetInstructionSize: Fix `41 81 7c ...` to return
 9.

---
 compiler-rt/lib/interception/interception_win.cpp            | 5 ++++-
 compiler-rt/lib/interception/tests/interception_win_test.cpp | 1 +
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/compiler-rt/lib/interception/interception_win.cpp b/compiler-rt/lib/interception/interception_win.cpp
index 93886e79fd88c8..cfa38fe702ebcd 100644
--- a/compiler-rt/lib/interception/interception_win.cpp
+++ b/compiler-rt/lib/interception/interception_win.cpp
@@ -808,7 +808,6 @@ static size_t GetInstructionSize(uptr address, size_t* rel_offset = nullptr) {
     case 0x798141:  // 41 81 79 XX YY YY YY YY : cmp DWORD PTR [r9+YY], XX XX XX XX
     case 0x7a8141:  // 41 81 7a XX YY YY YY YY : cmp DWORD PTR [r10+YY], XX XX XX XX
     case 0x7b8141:  // 41 81 7b XX YY YY YY YY : cmp DWORD PTR [r11+YY], XX XX XX XX
-    case 0x7c8141:  // 41 81 7c XX YY YY YY YY : cmp DWORD PTR [r12+YY], XX XX XX XX
     case 0x7d8141:  // 41 81 7d XX YY YY YY YY : cmp DWORD PTR [r13+YY], XX XX XX XX
     case 0x7e8141:  // 41 81 7e XX YY YY YY YY : cmp DWORD PTR [r14+YY], XX XX XX XX
     case 0x7f8141:  // 41 81 7f YY XX XX XX XX : cmp DWORD PTR [r15+YY], XX XX XX XX
@@ -835,6 +834,10 @@ static size_t GetInstructionSize(uptr address, size_t* rel_offset = nullptr) {
     case 0x2444c7:    // C7 44 24 XX YY YY YY YY
                       //   mov dword ptr [rsp + XX], YYYYYYYY
       return 8;
+
+    case 0x7c8141:  // 41 81 7c ZZ YY XX XX XX XX
+                    // cmp DWORD PTR [reg+reg*n+YY], XX XX XX XX
+      return 9;
   }
 
   switch (*(u32*)(address)) {
diff --git a/compiler-rt/lib/interception/tests/interception_win_test.cpp b/compiler-rt/lib/interception/tests/interception_win_test.cpp
index 3c60d9c6f49df9..ca61ffd4dd4604 100644
--- a/compiler-rt/lib/interception/tests/interception_win_test.cpp
+++ b/compiler-rt/lib/interception/tests/interception_win_test.cpp
@@ -989,6 +989,7 @@ const struct InstructionSizeData {
     { 8, {0x41, 0x81, 0x7f, 0x73, 0x74, 0x75, 0x76, 0x77}, 0, "41 81 7f YY XX XX XX XX : cmp DWORD PTR [r15+YY], XX XX XX XX"},
     { 8, {0x81, 0x7c, 0x24, 0x73, 0x74, 0x75, 0x76, 0x77}, 0, "81 7c 24 YY XX XX XX XX : cmp DWORD PTR [rsp+YY], XX XX XX XX"},
     { 8, {0xc7, 0x44, 0x24, 0x73, 0x74, 0x75, 0x76, 0x77}, 0, "C7 44 24 XX YY YY YY YY : mov dword ptr [rsp + XX], YYYYYYYY"},
+    { 9, {0x41, 0x81, 0x7c, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78}, 0, "41 81 7c ZZ YY XX XX XX XX : cmp DWORD PTR [reg+reg*n+YY], XX XX XX XX"},
     { 9, {0xA1, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78}, 0, "A1 XX XX XX XX XX XX XX XX : movabs eax, dword ptr ds:[XXXXXXXX]"},
 #else
     // sorted list