Bytecode Interpreter: Fix IntegralAP/Floating memory leaks

[tbaederr]

When creating new IntegralAP (or also Floating) values, they allocate heap memory, which might not get cleaned up when we interrupt interpretation and the integral stays on the stack. We never call the destructor.

This code:

int ctz48 = __builtin_ctzg((unsigned __int128)0);

produces a memory leak:

Direct leak of 16 byte(s) in 1 object(s) allocated from:
    #0 0x0000003e2c41 in operator new[](unsigned long) (/home/tbaeder/code/llvm-project/build/bin/clang-21+0x3e2c41) (BuildId: 616e3f3e5634af4d767394e4e2f35f78358eaebd)
    #1 0x7f05a3cdb67e in getMemory(unsigned int) /home/tbaeder/code/llvm-project/llvm/lib/Support/APInt.cpp:43:10
    #2 0x7f05a3cdb78f in llvm::APInt::initSlowCase(llvm::APInt const&) /home/tbaeder/code/llvm-project/llvm/lib/Support/APInt.cpp:87:12
    #3 0x7f05dd9c27ea in llvm::APInt::APInt(llvm::APInt const&) /home/tbaeder/code/llvm-project/llvm/include/llvm/ADT/APInt.h:180:7
    #4 0x7f05e007a03c in clang::interp::IntegralAP<false>::IntegralAP(llvm::APInt) /home/tbaeder/code/llvm-project/clang/lib/AST/ByteCode/IntegralAP.h:62:25
    #5 0x7f05e04e4eb7 in clang::interp::IntegralAP<false> clang::interp::IntegralAP<false>::from<32u, true>(clang::interp::Integral<32u, true>, unsigned int) /home/tbaeder/code/llvm-project/clang/lib/AST/ByteCode/IntegralAP.h:115:12
    #6 0x7f05e032b3fc in bool clang::interp::CastAP<(clang::interp::PrimType)4, clang::interp::Integral<32u, true>>(clang::interp::InterpState&, clang::interp::CodePtr, unsigned int) /home/tbaeder/code/llvm-project/clang/lib/AST/ByteCode/Interp.h:2266:7
    #7 0x7f05e02679de in clang::interp::EvalEmitter::emitCastAPSint32(unsigned int, clang::interp::SourceInfo const&) /home/tbaeder/code/llvm-project/build/tools/clang/lib/AST/Opcodes.inc:6657:10

I think we should allocate the memory ourselves, like APNumericStorage does.

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Timm Baeder (tbaederr)

When creating new `IntegralAP` (or also `Floating`) values, they allocate heap memory, which _might_ not get cleaned up when we interrupt interpretation and the integral stays on the stack. We never call the destructor.

This code:

int ctz48 = __builtin_ctzg((unsigned __int128)0);

produces a memory leak:

Direct leak of 16 byte(s) in 1 object(s) allocated from:
    #<!-- -->0 0x0000003e2c41 in operator new[](unsigned long) (/home/tbaeder/code/llvm-project/build/bin/clang-21+0x3e2c41) (BuildId: 616e3f3e5634af4d767394e4e2f35f78358eaebd)
    #<!-- -->1 0x7f05a3cdb67e in getMemory(unsigned int) /home/tbaeder/code/llvm-project/llvm/lib/Support/APInt.cpp:43:10
    #<!-- -->2 0x7f05a3cdb78f in llvm::APInt::initSlowCase(llvm::APInt const&amp;) /home/tbaeder/code/llvm-project/llvm/lib/Support/APInt.cpp:87:12
    #<!-- -->3 0x7f05dd9c27ea in llvm::APInt::APInt(llvm::APInt const&amp;) /home/tbaeder/code/llvm-project/llvm/include/llvm/ADT/APInt.h:180:7
    #<!-- -->4 0x7f05e007a03c in clang::interp::IntegralAP&lt;false&gt;::IntegralAP(llvm::APInt) /home/tbaeder/code/llvm-project/clang/lib/AST/ByteCode/IntegralAP.h:62:25
    #<!-- -->5 0x7f05e04e4eb7 in clang::interp::IntegralAP&lt;false&gt; clang::interp::IntegralAP&lt;false&gt;::from&lt;32u, true&gt;(clang::interp::Integral&lt;32u, true&gt;, unsigned int) /home/tbaeder/code/llvm-project/clang/lib/AST/ByteCode/IntegralAP.h:115:12
    #<!-- -->6 0x7f05e032b3fc in bool clang::interp::CastAP&lt;(clang::interp::PrimType)4, clang::interp::Integral&lt;32u, true&gt;&gt;(clang::interp::InterpState&amp;, clang::interp::CodePtr, unsigned int) /home/tbaeder/code/llvm-project/clang/lib/AST/ByteCode/Interp.h:2266:7
    #<!-- -->7 0x7f05e02679de in clang::interp::EvalEmitter::emitCastAPSint32(unsigned int, clang::interp::SourceInfo const&amp;) /home/tbaeder/code/llvm-project/build/tools/clang/lib/AST/Opcodes.inc:6657:10

I think we should allocate the memory ourselves, like APNumericStorage does.