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<p class="MsoNormal">It’s simply wrong.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">On many 64-bit targets, it will appear to work anyway, depending on your luck, due to the way calling conventions works.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">-Eli<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><b>From:</b> llvm-dev <llvm-dev-bounces@lists.llvm.org>
<b>On Behalf Of </b>Jason -Zhong Sheng- Hu via llvm-dev<br>
<b>Sent:</b> Tuesday, April 14, 2020 6:49 PM<br>
<b>To:</b> llvm-dev@lists.llvm.org<br>
<b>Subject:</b> [EXT] [llvm-dev] question on the signature of malloc<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;color:black">Hi all,<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;color:black">consider the following function from Core.cpp in LLVM 9.0.0:<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;font-family:"Courier New";color:black">LLVMValueRef LLVMBuildMalloc(LLVMBuilderRef B, LLVMTypeRef Ty,</span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;font-family:"Courier New";color:black"> const char *Name) {</span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;font-family:"Courier New";color:black;background:yellow"> Type* ITy = Type::getInt32Ty(unwrap(B)->GetInsertBlock()->getContext());</span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;font-family:"Courier New";color:black"> Constant* AllocSize = ConstantExpr::getSizeOf(unwrap(Ty));</span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;font-family:"Courier New";color:black"> AllocSize = ConstantExpr::getTruncOrBitCast(AllocSize, ITy);</span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;font-family:"Courier New";color:black"> Instruction* Malloc = CallInst::CreateMalloc(unwrap(B)->GetInsertBlock(),</span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;font-family:"Courier New";color:black"> ITy, unwrap(Ty), AllocSize,</span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;font-family:"Courier New";color:black"> nullptr, nullptr, "");</span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;font-family:"Courier New";color:black"> return wrap(unwrap(B)->Insert(Malloc, Twine(Name)));</span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;font-family:"Courier New";color:black">}</span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;color:black">In this code I highlighted the line which I have question on. the signature of malloc is<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;font-family:"Courier New";color:black">void *malloc(size_t size);</span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in;background:white"><span style="font-size:12.0pt;color:black">is this suspiciously wrong that this builder assumes size_t is 32 bit int? will LLVM backend smart enough to link the right one, which in 64 bit system
is 64 bit int?<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><b><span style="font-size:12.0pt;color:black">Thanks,</span></b><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><b><span style="font-size:12.0pt;color:black">Jason Hu</span></b><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><b><span style="font-size:12.0pt;color:black"><a href="https://hustmphrrr.github.io/">https://hustmphrrr.github.io/</a></span></b><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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