[clang][bytecode] Fix bit casts to IntAP types

[tbaederr]

They were left out.

Fixes #153920

[llvmbot]

@llvm/pr-subscribers-clang

Author: Timm Baeder (tbaederr)

Changes

They were left out.

Fixes #153920

---

Full diff: https://github.com/llvm/llvm-project/pull/158509.diff

2 Files Affected:

• (modified) clang/lib/AST/ByteCode/InterpBuiltinBitCast.cpp (+21-7)
• (modified) clang/test/AST/ByteCode/builtin-bit-cast.cpp (+41)

diff --git a/clang/lib/AST/ByteCode/InterpBuiltinBitCast.cpp b/clang/lib/AST/ByteCode/InterpBuiltinBitCast.cpp
index feac97d4b1a69..4bd9c66fc9974 100644
--- a/clang/lib/AST/ByteCode/InterpBuiltinBitCast.cpp
+++ b/clang/lib/AST/ByteCode/InterpBuiltinBitCast.cpp
@@ -441,13 +441,27 @@ bool clang::interp::DoBitCastPtr(InterpState &S, CodePtr OpPC,
         if (llvm::sys::IsBigEndianHost)
           swapBytes(Memory.get(), FullBitWidth.roundToBytes());
 
-        BITCAST_TYPE_SWITCH_FIXED_SIZE(T, {
-          if (BitWidth.nonZero())
-            P.deref<T>() = T::bitcastFromMemory(Memory.get(), T::bitWidth())
-                               .truncate(BitWidth.getQuantity());
-          else
-            P.deref<T>() = T::zero();
-        });
+        if (T == PT_IntAPS) {
+          P.deref<IntegralAP<true>>() =
+              S.allocAP<IntegralAP<true>>(FullBitWidth.getQuantity());
+          IntegralAP<true>::bitcastFromMemory(Memory.get(),
+                                              FullBitWidth.getQuantity(),
+                                              &P.deref<IntegralAP<true>>());
+        } else if (T == PT_IntAP) {
+          P.deref<IntegralAP<false>>() =
+              S.allocAP<IntegralAP<false>>(FullBitWidth.getQuantity());
+          IntegralAP<false>::bitcastFromMemory(Memory.get(),
+                                               FullBitWidth.getQuantity(),
+                                               &P.deref<IntegralAP<false>>());
+        } else {
+          BITCAST_TYPE_SWITCH_FIXED_SIZE(T, {
+            if (BitWidth.nonZero())
+              P.deref<T>() = T::bitcastFromMemory(Memory.get(), T::bitWidth())
+                                 .truncate(BitWidth.getQuantity());
+            else
+              P.deref<T>() = T::zero();
+          });
+        }
         P.initialize();
         return true;
       });
diff --git a/clang/test/AST/ByteCode/builtin-bit-cast.cpp b/clang/test/AST/ByteCode/builtin-bit-cast.cpp
index bc356b0b6e122..fede780fd66ec 100644
--- a/clang/test/AST/ByteCode/builtin-bit-cast.cpp
+++ b/clang/test/AST/ByteCode/builtin-bit-cast.cpp
@@ -529,3 +529,44 @@ constexpr const intptr_t &returns_local() { return 0L; }
 // both-error@+2 {{constexpr variable 'test_nullptr_bad' must be initialized by a constant expression}}
 // both-note@+1 {{read of temporary whose lifetime has ended}}
 constexpr nullptr_t test_nullptr_bad = __builtin_bit_cast(nullptr_t, returns_local());
+
+namespace VectorCast {
+  typedef unsigned X          __attribute__ ((vector_size (64)));
+  typedef unsigned __int128 Y __attribute__ ((vector_size (64)));
+  constexpr int test() {
+    X x = {0};
+    Y y = x;
+
+    X x2 = y;
+
+    return 0;
+  }
+  static_assert(test() == 0);
+
+  typedef int X2      __attribute__ ((vector_size (64)));
+  typedef __int128 Y2 __attribute__ ((vector_size (64)));
+  constexpr int test2() {
+    X2 x = {0};
+    Y2 y = x;
+
+    X2 x2 = y;
+
+    return 0;
+  }
+  static_assert(test2() == 0);
+
+  struct S {
+    unsigned __int128 a : 3;
+  };
+  constexpr S s = __builtin_bit_cast(S, (__int128)12); // ref-error {{must be initialized by a constant expression}} \
+                                                       // ref-note {{constexpr bit_cast involving bit-field is not yet supported}} \
+                                                       // ref-note {{declared here}}
+#if LITTLE_END
+  static_assert(s.a == 4); // ref-error {{not an integral constant expression}} \
+                           // ref-note {{initializer of 's' is not a constant expression}}
+#else
+  static_assert(s.a == 0); // ref-error {{not an integral constant expression}} \
+                           // ref-note {{initializer of 's' is not a constant expression}}
+#endif
+
+}

[llvm-ci]

LLVM Buildbot has detected a new failure on builder clang-armv8-quick running on linaro-clang-armv8-quick while building clang at step 5 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/154/builds/21492

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

Step 5 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'Clang :: AST/ByteCode/builtin-bit-cast.cpp' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
/home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/clang -cc1 -internal-isystem /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/lib/clang/22/include -nostdsysteminc -verify=ref,both -std=c++2a -fsyntax-only /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/AST/ByteCode/builtin-bit-cast.cpp # RUN: at line 1
+ /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/clang -cc1 -internal-isystem /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/lib/clang/22/include -nostdsysteminc -verify=ref,both -std=c++2a -fsyntax-only /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/AST/ByteCode/builtin-bit-cast.cpp
error: diagnostics with 'error' severity seen but not expected: 
  File /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/AST/ByteCode/builtin-bit-cast.cpp Line 535: __int128 is not supported on this target
  File /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/AST/ByteCode/builtin-bit-cast.cpp Line 547: __int128 is not supported on this target
  File /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/AST/ByteCode/builtin-bit-cast.cpp Line 559: __int128 is not supported on this target
  File /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/AST/ByteCode/builtin-bit-cast.cpp Line 561: __int128 is not supported on this target
4 errors generated.

--

********************

[DavidSpickett]

The above failure is because the bot is 32-bit Armv8-a, I expect this would fail on x86 32-bit as well. I think you could use the lit feature clang-target-64-bits along with %if{ ... } to make the host triple line conditional. I don't completely understand what clang-target-64-bits implies though.

[tbaederr]

That should be fixed by 24b5867 already

[DavidSpickett]

Is is, thanks!

[tuliom]

Heads up: I've bisected a regression on s390x to this PR.
I reported it as #160374.