[PATCH] D79249: [NOT FOR REVIEW] Experimental support for zero-or-trap behavior foruninitialized variables.

[Richard Smith - zygoloid via Phabricator via llvm-commits]

rsmith created this revision.
Herald added subscribers: llvm-commits, cfe-commits, jdoerfert, hiraditya.
Herald added projects: clang, LLVM.
rsmith updated this revision to Diff 261511.
rsmith added a comment.

- The second operand of 'store' is the pointer, not the first.


Add <type> @llvm.trapping.<type>(<type>) intrinsic.

This is intended to produce either the given value or, if we can trace a
use of the value to an instruction with side-effects, a trap.
Notionally, it behaves as a nondeterministic choice between the given
value and poison, where the choice is made angelically such that the
given value is always chosen when the program does not reach a trap.

Simplify trapping(x) and convert it into traps where possible.

Update Clang CodeGen to produce trapping(x) in trivial auto var init
mode.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D79249

Files:
  clang/lib/CodeGen/CGDecl.cpp
  llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
  llvm/include/llvm/IR/Intrinsics.td
  llvm/lib/CodeGen/CodeGenPrepare.cpp
  llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
  llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
  llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
  llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
  llvm/lib/Transforms/InstCombine/InstCombineInternal.h
  llvm/lib/Transforms/Scalar/LowerConstantIntrinsics.cpp

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