[clang] [CLANG] Resolves crash on invalid loop vectorize_width (PR #169473)

[Ebin Jose via cfe-commits]

https://github.com/ebinjose02 updated https://github.com/llvm/llvm-project/pull/169473

>From 73761f8d62f505901eef4b845cccca98b1bc21ee Mon Sep 17 00:00:00 2001
From: ebinjose02 <ebin371 at gmail.com>
Date: Tue, 25 Nov 2025 08:54:39 +0000
Subject: [PATCH 1/2] Fixes #166325 Diagnose malformed '#pragma clang loop
 vectorize_width' lists. Avoids crash in HandlePragmaLoopHint, emit clear
 diagnostic and added regression test.

---
 clang/lib/Parse/ParsePragma.cpp             |  2 +-
 clang/test/Parser/pragma-loop-vectorize.cpp | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)
 create mode 100644 clang/test/Parser/pragma-loop-vectorize.cpp

diff --git a/clang/lib/Parse/ParsePragma.cpp b/clang/lib/Parse/ParsePragma.cpp
index 7c2b9280f0b76..7e8b339f5be49 100644
--- a/clang/lib/Parse/ParsePragma.cpp
+++ b/clang/lib/Parse/ParsePragma.cpp
@@ -1531,7 +1531,7 @@ bool Parser::HandlePragmaLoopHint(LoopHint &Hint) {
         PP.Lex(Tok); // ,
 
         StateInfo = Tok.getIdentifierInfo();
-        IsScalableStr = StateInfo->getName();
+        IsScalableStr = StateInfo ? StateInfo->getName() : "";
 
         if (IsScalableStr != "scalable" && IsScalableStr != "fixed") {
           Diag(Tok.getLocation(),
diff --git a/clang/test/Parser/pragma-loop-vectorize.cpp b/clang/test/Parser/pragma-loop-vectorize.cpp
new file mode 100644
index 0000000000000..39f7e84323f5f
--- /dev/null
+++ b/clang/test/Parser/pragma-loop-vectorize.cpp
@@ -0,0 +1,13 @@
+// RUN: not %clang_cc1 -fsyntax-only %s 2>&1 | FileCheck %s
+
+void sum_vector(unsigned int A[], unsigned int B[], unsigned int sum[]) {
+    #pragma clang loop vectorize_width(4,8,16) vectorize(assume_safety)
+    for (int k = 0; k < 64; k++) {
+        sum[k] = A[k] + 3 * B[k];
+    }
+}
+
+// CHECK: error: vectorize_width loop hint malformed; use
+// CHECK-SAME: vectorize_width(X, fixed) or vectorize_width(X, scalable) where X is an integer, or
+// CHECK-SAME: vectorize_width('fixed' or 'scalable')
+// CHECK: warning: extra tokens at end of '#pragma clang loop vectorize_width'

>From 4baff073cbdc36d854177e16151e7a309d475f2b Mon Sep 17 00:00:00 2001
From: ebinjose02 <ebin371 at gmail.com>
Date: Wed, 26 Nov 2025 05:45:15 +0000
Subject: [PATCH 2/2] Added a documentation Updated the test file

---
 clang/docs/ReleaseNotes.rst                 |  3 ++-
 clang/test/Parser/pragma-loop-vectorize.cpp | 18 ++++++++----------
 2 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 439e47b209b2f..da68148ddccde 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -722,7 +722,8 @@ Crash and bug fixes
   ``[[assume(expr)]]`` attribute was enclosed in parentheses.  (#GH151529)
 - Fixed a crash when parsing ``#embed`` parameters with unmatched closing brackets. (#GH152829)
 - Fixed a crash when compiling ``__real__`` or ``__imag__`` unary operator on scalar value with type promotion. (#GH160583)
-
+- Fixed a crash when parsing malformed #pragma clang loop vectorize_width(4,8,16)
+  by diagnosing invalid comma-separated argument lists. (#GH166325)
 Improvements
 ^^^^^^^^^^^^
 
diff --git a/clang/test/Parser/pragma-loop-vectorize.cpp b/clang/test/Parser/pragma-loop-vectorize.cpp
index 39f7e84323f5f..94cc77aa37d4c 100644
--- a/clang/test/Parser/pragma-loop-vectorize.cpp
+++ b/clang/test/Parser/pragma-loop-vectorize.cpp
@@ -1,13 +1,11 @@
-// RUN: not %clang_cc1 -fsyntax-only %s 2>&1 | FileCheck %s
+// RUN: %clang_cc1 -fsyntax-only %s -verify
 
 void sum_vector(unsigned int A[], unsigned int B[], unsigned int sum[]) {
-    #pragma clang loop vectorize_width(4,8,16) vectorize(assume_safety)
-    for (int k = 0; k < 64; k++) {
-        sum[k] = A[k] + 3 * B[k];
-    }
-}
+  #pragma clang loop vectorize_width(4,8,16) vectorize(assume_safety)
+  // expected-error at -1 {{vectorize_width loop hint malformed; use vectorize_width(X, fixed) or vectorize_width(X, scalable) where X is an integer, or vectorize_width('fixed' or 'scalable')}}
+  // expected-warning at -2 {{extra tokens at end of '#pragma clang loop vectorize_width' - ignored}}
 
-// CHECK: error: vectorize_width loop hint malformed; use
-// CHECK-SAME: vectorize_width(X, fixed) or vectorize_width(X, scalable) where X is an integer, or
-// CHECK-SAME: vectorize_width('fixed' or 'scalable')
-// CHECK: warning: extra tokens at end of '#pragma clang loop vectorize_width'
+  for (int k = 0; k < 64; k++) {
+    sum[k] = A[k] + 3 * B[k];
+  }
+}