[llvm] 99fb65f - [NFC]Add assert to avoid possibly deref nullptr (#65564)

[via llvm-commits]

Author: XinWang10
Date: 2023-09-08T10:10:09+08:00
New Revision: 99fb65fa7a65b9a3f961d6ef715324c2f8637766

URL: https://github.com/llvm/llvm-project/commit/99fb65fa7a65b9a3f961d6ef715324c2f8637766
DIFF: https://github.com/llvm/llvm-project/commit/99fb65fa7a65b9a3f961d6ef715324c2f8637766.diff

LOG: [NFC]Add assert to avoid possibly deref nullptr (#65564)

These 2 functions could be called by AsmPrinter::doInitialization in
AsmPrinter.cpp. doInitialization init MMI in the beginning`MMI = MMIWP ?
&MMIWP->getMMI() : nullptr;`, MMI has the possibility to be nullptr,
which could make the later deref crash. I think in most time MMI could
not be nullptr, but from the view of function implementation, it could
be, so I'd like to add assert to it, if this could be a problem, then we
could avoid crash.

Added: 
    

Modified: 
    llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
    llvm/lib/Target/X86/X86AsmPrinter.cpp

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
index 083d1503330a390..bb210527754d22d 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
@@ -400,6 +400,7 @@ void AsmPrinter::emitInlineAsm(const MachineInstr *MI) const {
         "Reserved registers on the clobber list may not be "
         "preserved across the asm statement, and clobbering them may "
         "lead to undefined behaviour.";
+    assert(MMI && "MMI can not be nullptr!");
     MMI->getModule()->getContext().diagnose(DiagnosticInfoInlineAsm(
         LocCookie, Msg, DiagnosticSeverity::DS_Warning));
     MMI->getModule()->getContext().diagnose(

diff  --git a/llvm/lib/Target/X86/X86AsmPrinter.cpp b/llvm/lib/Target/X86/X86AsmPrinter.cpp
index bb94444525fb89a..d09732274f5c1df 100644
--- a/llvm/lib/Target/X86/X86AsmPrinter.cpp
+++ b/llvm/lib/Target/X86/X86AsmPrinter.cpp
@@ -769,6 +769,7 @@ void X86AsmPrinter::emitStartOfAsmFile(Module &M) {
       if (!TT.isArch32Bit() && !TT.isArch64Bit())
         llvm_unreachable("CFProtection used on invalid architecture!");
       MCSection *Cur = OutStreamer->getCurrentSectionOnly();
+      assert(MMI && "MMI can not be nullptr!");
       MCSection *Nt = MMI->getContext().getELFSection(
           ".note.gnu.property", ELF::SHT_NOTE, ELF::SHF_ALLOC);
       OutStreamer->switchSection(Nt);