AArch64: Safely handle the incoming sret call argument.

This adds a safe interface to the machine independent InputArg struct
for accessing the index of the original (IR-level) argument. When a
non-native return type is lowered, we generate the hidden
machine-level sret argument on-the-fly. Before this fix, we were
representing this argument as OrigArgIndex == 0, which is an outright
lie. In particular this crashed in the AArch64 backend where we
actually try to access the type of the original argument.

Now we use a sentinel value for machine arguments that have no
original argument index. AArch64, ARM, Mips, and PPC now check for this
case before accessing the original argument.

Fixes <rdar://19792160> Null pointer assertion in AArch64TargetLowering

llvm-svn: 229413

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/Target/Mips/MipsCCState.cpp b/llvm/lib/Target/Mips/MipsCCState.cpp
index e18cc8b1f7b..b8081295ca6 100644
--- a/llvm/lib/Target/Mips/MipsCCState.cpp
+++ b/llvm/lib/Target/Mips/MipsCCState.cpp
@@ -132,8 +132,8 @@ void MipsCCState::PreAnalyzeFormalArgumentsForF128(
       continue;
     }
 
-    assert(Ins[i].OrigArgIndex < MF.getFunction()->arg_size());
-    std::advance(FuncArg, Ins[i].OrigArgIndex);
+    assert(Ins[i].getOrigArgIndex() < MF.getFunction()->arg_size());
+    std::advance(FuncArg, Ins[i].getOrigArgIndex());
 
     OriginalArgWasF128.push_back(
         originalTypeIsF128(FuncArg->getType(), nullptr));