[PATCH] D74229: [Clang] Cover '#pragma clang __debug overflow_stack' in tests

[Alexandre Ganea via Phabricator via cfe-commits]

aganea created this revision.
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================
Comment at: clang/lib/Lex/Pragma.cpp:1148
 
+#ifdef __clang__
+  __attribute__((optnone))
----------------
Would it be better if we had something like `LLVM_[DISABLE|ENABLE]_OPT` in `Compiler.h` instead of the #ifdefs? That would map to `#pragma clang optimize [off|on]` (and corresponding #pragma on MSVC/GCC). Note that there's no way I know of to disable optimizations on a per-function basis on MSVC.


Previously, `#pragma clang __debug overflow_stack` wasn't really working, the function was simply looping and not overflowing.
I tested this in various configurations, with Clang 9, MSVC 2017/2019 and GCC 9 on Ubuntu.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D74229

Files:
  clang/lib/Lex/Pragma.cpp
  clang/test/Driver/crash-report.c


Index: clang/test/Driver/crash-report.c
===================================================================
--- clang/test/Driver/crash-report.c
+++ clang/test/Driver/crash-report.c
@@ -21,12 +21,20 @@
 // RUN: cat %t/crash-report-*.c | FileCheck --check-prefix=CHECKSRC %s
 // RUN: cat %t/crash-report-*.sh | FileCheck --check-prefix=CHECKSH %s
 
+// RUN: env TMPDIR=%t TEMP=%t TMP=%t RC_DEBUG_OPTIONS=1                  \
+// RUN:  CC_PRINT_HEADERS=1 CC_LOG_DIAGNOSTICS=1                         \
+// RUN:  not %clang %s @%t.rsp -DOVERFLOW 2>&1 | FileCheck %s
+// RUN: cat %t/crash-report-*.c | FileCheck --check-prefix=CHECKSRC %s
+// RUN: cat %t/crash-report-*.sh | FileCheck --check-prefix=CHECKSH %s
+
 // REQUIRES: crash-recovery
 
 #ifdef PARSER
 #pragma clang __debug parser_crash
 #elif CRASH
 #pragma clang __debug crash
+#elif OVERFLOW
+#pragma clang __debug overflow_stack
 #endif
 
 // CHECK: Preprocessed source(s) and associated run script(s) are located at:
Index: clang/lib/Lex/Pragma.cpp
===================================================================
--- clang/lib/Lex/Pragma.cpp
+++ clang/lib/Lex/Pragma.cpp
@@ -1145,16 +1145,24 @@
                         /*IsReinject=*/false);
   }
 
+#ifdef __clang__
+  __attribute__((optnone))
+#elif __GNUC__
+  __attribute__((optimize("O0")))
+#elif _MSC_VER
 // Disable MSVC warning about runtime stack overflow.
-#ifdef _MSC_VER
-    #pragma warning(disable : 4717)
+#pragma warning(disable : 4717)
+#pragma optimize("", off)
 #endif
-  static void DebugOverflowStack(void (*P)() = nullptr) {
-    void (*volatile Self)(void(*P)()) = DebugOverflowStack;
-    Self(reinterpret_cast<void(*)()>(Self));
-  }
-#ifdef _MSC_VER
-    #pragma warning(default : 4717)
+  static void
+  DebugOverflowStack(void (*P)() = nullptr, unsigned *V = nullptr) {
+    unsigned A[16384]{1};
+    void (*volatile Self)(void (*P)(), unsigned *) = DebugOverflowStack;
+    Self(reinterpret_cast<void (*)()>(Self), A);
+  }
+#if !defined(__clang__) && defined(_MSC_VER)
+#pragma optimize("", on)
+#pragma warning(default : 4717)
 #endif
 };
 


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