https://github.com/tbaederr created
https://github.com/llvm/llvm-project/pull/114485
None
>From ef34e3ce22103178513db8bb9565dec1511c1463 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbae...@redhat.com>
Date: Fri, 1 Nov 2024 00:16:28 +0100
Subject: [PATCH] [clang][bytecode] Implement bitcasts to floating-point values
---
clang/lib/AST/ByteCode/Interp.h | 3 +-
clang/test/AST/ByteCode/builtin-bit-cast.cpp | 56 +++++++++++++++++++-
2 files changed, 57 insertions(+), 2 deletions(-)
diff --git a/clang/lib/AST/ByteCode/Interp.h b/clang/lib/AST/ByteCode/Interp.h
index ade6f7424b1fd6..52d3a19ca99593 100644
--- a/clang/lib/AST/ByteCode/Interp.h
+++ b/clang/lib/AST/ByteCode/Interp.h
@@ -3062,7 +3062,8 @@ inline bool BitCast(InterpState &S, CodePtr OpPC, bool
TargetIsUCharOrByte,
return false;
if constexpr (std::is_same_v<T, Floating>) {
- assert(false && "Implement bitcasting to a floating type");
+ assert(Sem);
+ S.Stk.push<Floating>(T::bitcastFromMemory(Buff.data(), *Sem));
} else {
assert(!Sem);
S.Stk.push<T>(T::bitcastFromMemory(Buff.data(), ResultBitWidth));
diff --git a/clang/test/AST/ByteCode/builtin-bit-cast.cpp
b/clang/test/AST/ByteCode/builtin-bit-cast.cpp
index 58cf486833412f..319405c60cbad0 100644
--- a/clang/test/AST/ByteCode/builtin-bit-cast.cpp
+++ b/clang/test/AST/ByteCode/builtin-bit-cast.cpp
@@ -103,7 +103,7 @@ namespace simple {
static_assert(check_round_trip<unsigned>((int)0x12345678));
static_assert(check_round_trip<unsigned>((int)0x87654321));
static_assert(check_round_trip<unsigned>((int)0x0C05FEFE));
- // static_assert(round_trip<float>((int)0x0C05FEFE));
+ static_assert(round_trip<float>((int)0x0C05FEFE));
/// This works in GCC and in the bytecode interpreter, but the current
interpreter
@@ -449,3 +449,57 @@ struct ref_mem {
// both-error@+2 {{constexpr variable 'run_ref_mem' must be initialized by a
constant expression}}
// both-note@+1 {{bit_cast from a type with a reference member is not allowed
in a constant expression}}
constexpr intptr_t run_ref_mem = __builtin_bit_cast(intptr_t,
ref_mem{global_int});
+
+namespace test_long_double {
+#ifdef __x86_64
+#if 0
+constexpr __int128_t test_cast_to_int128 = bit_cast<__int128_t>((long
double)0); // expected-error{{must be initialized by a constant expression}}\
+
// expected-note{{in call}}
+#endif
+constexpr long double ld = 3.1425926539;
+
+struct bytes {
+ unsigned char d[16];
+};
+
+// static_assert(round_trip<bytes>(ld), "");
+
+static_assert(round_trip<long double>(10.0L));
+
+#if 0
+constexpr bool f(bool read_uninit) {
+ bytes b = bit_cast<bytes>(ld);
+ unsigned char ld_bytes[10] = {
+ 0x0, 0x48, 0x9f, 0x49, 0xf0,
+ 0x3c, 0x20, 0xc9, 0x0, 0x40,
+ };
+
+ for (int i = 0; i != 10; ++i)
+ if (ld_bytes[i] != b.d[i])
+ return false;
+
+ if (read_uninit && b.d[10]) // expected-note{{read of uninitialized object
is not allowed in a constant expression}}
+ return false;
+
+ return true;
+}
+
+static_assert(f(/*read_uninit=*/false), "");
+static_assert(f(/*read_uninit=*/true), ""); // expected-error{{static
assertion expression is not an integral constant expression}} \
+ // expected-note{{in call to
'f(true)'}}
+#endif
+constexpr bytes ld539 = {
+ 0x0, 0x0, 0x0, 0x0,
+ 0x0, 0x0, 0xc0, 0x86,
+ 0x8, 0x40, 0x0, 0x0,
+ 0x0, 0x0, 0x0, 0x0,
+};
+
+constexpr long double fivehundredandthirtynine = 539.0;
+
+static_assert(bit_cast<long double>(ld539) == fivehundredandthirtynine, "");
+
+#else
+static_assert(round_trip<__int128_t>(34.0L));
+#endif
+}
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