[clang][bytecode] Reject constexpr-unknown pointers from Inc ops

[tbaederr]

We used to accept c++ as a known value here, causing wrong codegen.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Timm Baeder (tbaederr)

Changes

We used to accept c++ as a known value here, causing wrong codegen.

---

Full diff: https://github.com/llvm/llvm-project/pull/135548.diff

2 Files Affected:

• (modified) clang/lib/AST/ByteCode/Interp.h (+5)
• (modified) clang/test/AST/ByteCode/codegen.cpp (+10-1)

diff --git a/clang/lib/AST/ByteCode/Interp.h b/clang/lib/AST/ByteCode/Interp.h
index 4e84dcc8d551d..b4e15b3ffbe68 100644
--- a/clang/lib/AST/ByteCode/Interp.h
+++ b/clang/lib/AST/ByteCode/Interp.h
@@ -771,6 +771,11 @@ bool IncDecHelper(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
                   bool CanOverflow) {
   assert(!Ptr.isDummy());
 
+  if (!S.inConstantContext()) {
+    if (isConstexprUnknown(Ptr))
+      return false;
+  }
+
   if constexpr (std::is_same_v<T, Boolean>) {
     if (!S.getLangOpts().CPlusPlus14)
       return Invalid(S, OpPC);
diff --git a/clang/test/AST/ByteCode/codegen.cpp b/clang/test/AST/ByteCode/codegen.cpp
index ea2c812f30f6f..7c853a20362b8 100644
--- a/clang/test/AST/ByteCode/codegen.cpp
+++ b/clang/test/AST/ByteCode/codegen.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple x86_64-linux -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-linux -emit-llvm -o - %s                                         | FileCheck %s
 // RUN: %clang_cc1 -triple x86_64-linux -emit-llvm -o - %s -fexperimental-new-constant-interpreter | FileCheck %s
 
 #ifdef __SIZEOF_INT128__
@@ -95,3 +95,12 @@ void f(A *a) {
   // CHECK: call void @_ZN1AD1Ev(
   A::E e3 = A().Foo;
 }
+
+int notdead() {
+  auto l = [c=0]() mutable {
+    return  c++ < 5 ? 10 : 12;
+  };
+  return l();
+}
+// CHECK: _ZZ7notdeadvEN3$_0clEv
+// CHECK: ret i32 %cond

[llvm-ci]

LLVM Buildbot has detected a new failure on builder flang-x86_64-windows running on minipc-ryzen-win while building clang at step 6 "build-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/166/builds/952

Here is the relevant piece of the build log for the reference

Step 6 (build-unified-tree) failure: build (failure)
...
39.742 [116/12/22] Linking CXX executable bin\sancov.exe
39.778 [115/12/23] Linking CXX executable bin\sanstats.exe
39.819 [114/12/24] Linking CXX executable bin\llvm-xray.exe
39.821 [113/12/25] Linking CXX executable bin\obj2yaml.exe
39.841 [112/12/26] Generating ../../bin/llvm-dlltool.exe
41.429 [111/12/27] Linking CXX executable bin\llvm-objcopy.exe
41.938 [110/12/28] Linking CXX executable bin\llvm-dwarfdump.exe
43.870 [109/12/29] Linking CXX executable bin\llvm-readobj.exe
44.419 [108/12/30] Linking CXX executable bin\llvm-ctxprof-util.exe
45.339 [107/12/31] Linking CXX executable bin\mlir-opt.exe
FAILED: bin/mlir-opt.exe 
C:\Windows\system32\cmd.exe /C "cd . && "C:\Program Files\CMake\bin\cmake.exe" -E vs_link_exe --msvc-ver=1943 --intdir=tools\mlir\tools\mlir-opt\CMakeFiles\mlir-opt.dir --rc=C:\PROGRA~2\WI3CF2~1\10\bin\100220~1.0\x64\rc.exe --mt=C:\PROGRA~2\WI3CF2~1\10\bin\100220~1.0\x64\mt.exe --manifests  -- C:\PROGRA~1\MICROS~2\2022\COMMUN~1\VC\Tools\MSVC\1443~1.348\bin\Hostx64\x64\link.exe /nologo @CMakeFiles\mlir-opt.rsp  /out:bin\mlir-opt.exe /implib:lib\mlir-opt.lib /pdb:bin\mlir-opt.pdb /version:0.0 /machine:x64 /STACK:10000000 /INCREMENTAL:NO /subsystem:console && cd ."
LINK: command "C:\PROGRA~1\MICROS~2\2022\COMMUN~1\VC\Tools\MSVC\1443~1.348\bin\Hostx64\x64\link.exe /nologo @CMakeFiles\mlir-opt.rsp /out:bin\mlir-opt.exe /implib:lib\mlir-opt.lib /pdb:bin\mlir-opt.pdb /version:0.0 /machine:x64 /STACK:10000000 /INCREMENTAL:NO /subsystem:console /MANIFEST:EMBED,ID=1" failed (exit code 0) with the following output:

  Version 14.43.34809.0

  ExceptionCode            = C0000005
  ExceptionFlags           = 00000000
  ExceptionAddress         = 00007FF658EE36A2 (00007FF658EC0000) "C:\PROGRA~1\MICROS~2\2022\COMMUN~1\VC\Tools\MSVC\1443~1.348\bin\Hostx64\x64\link.exe"
  NumberParameters         = 00000002
  ExceptionInformation[ 0] = 0
  ExceptionInformation[ 1] = FFFFFFFFFFFFFFFF

CONTEXT:
  Rax    = 2A6DC610340  R8     = 4000000000000
  Rbx    = AAAAAAAAAAAAAAAB  R9     = 0
  Rcx    = 2C9  R10    = 2A6DD160138
  Rdx    = 2A6D6909630  R11    = C1
  Rsp    = DDD3BFBF40  R12    = 0
  Rbp    = DDD3BFC040  E13    = 2A6DECFAB00

  Rsi    = A64E  R14    = 3A64

  Rdi    = 2000  R15    = 2A6DFD9F478

  Rip    = 7FF658EE36A2  EFlags = 10206

  SegCs  = 33  SegDs  = 2B

  SegSs  = 2B  SegEs  = 2B

  SegFs  = 53  SegGs  = 2B

  Dr0    = 0  Dr3    = 0

  Dr1    = 0  Dr6    = 0

  Dr2    = 0  Dr7    = 0