From 47cf2affbdb8a8152b84965134282581692baace Mon Sep 17 00:00:00 2001 From: Sanjoy Das Date: Sat, 30 Apr 2016 00:55:59 +0000 Subject: [PATCH] [LowerGuardIntrinsics] Keep track of !make.implicit metadata If a guard call being lowered by LowerGuardIntrinsics has the `!make.implicit` metadata attached, then reattach the metadata to the branch in the resulting expanded form of the intrinsic. This allows us to implement null checks as guards and still get the benefit of implicit null checks. llvm-svn: 268148 --- llvm/docs/LangRef.rst | 7 ++++++- llvm/lib/Transforms/Scalar/LowerGuardIntrinsic.cpp | 3 +++ llvm/test/Transforms/LowerGuardIntrinsic/basic.ll | 12 ++++++++++++ 3 files changed, 21 insertions(+), 1 deletion(-) diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst index dc8b4d14bc02..7c6ff7a72c31 100644 --- a/llvm/docs/LangRef.rst +++ b/llvm/docs/LangRef.rst @@ -12375,7 +12375,7 @@ equivalent to: define void @llvm.experimental.guard(i1 %pred, ) { %realPred = and i1 %pred, undef - br i1 %realPred, label %continue, label %leave + br i1 %realPred, label %continue, label %leave [, !make.implicit !{}] leave: call void @llvm.experimental.deoptimize() [ "deopt"() ] @@ -12385,6 +12385,11 @@ equivalent to: ret void } + +with the optional ``[, !make.implicit !{}]`` present if and only if it +is present on the call site. For more details on ``!make.implicit``, +see :doc:`FaultMaps`. + In words, ``@llvm.experimental.guard`` executes the attached ``"deopt"`` continuation if (but **not** only if) its first argument is ``false``. Since the optimizer is allowed to replace the ``undef`` diff --git a/llvm/lib/Transforms/Scalar/LowerGuardIntrinsic.cpp b/llvm/lib/Transforms/Scalar/LowerGuardIntrinsic.cpp index a58346c2b1c7..7ba17069f426 100644 --- a/llvm/lib/Transforms/Scalar/LowerGuardIntrinsic.cpp +++ b/llvm/lib/Transforms/Scalar/LowerGuardIntrinsic.cpp @@ -56,6 +56,9 @@ static void MakeGuardControlFlowExplicit(Function *DeoptIntrinsic, CheckBI->getSuccessor(0)->setName("guarded"); CheckBI->getSuccessor(1)->setName("deopt"); + if (auto *MD = CI->getMetadata(LLVMContext::MD_make_implicit)) + CheckBI->setMetadata(LLVMContext::MD_make_implicit, MD); + IRBuilder<> B(DeoptBlockTerm); auto *DeoptCall = B.CreateCall(DeoptIntrinsic, Args, {DeoptOB}, ""); diff --git a/llvm/test/Transforms/LowerGuardIntrinsic/basic.ll b/llvm/test/Transforms/LowerGuardIntrinsic/basic.ll index ae696cf4269d..ade24eb7b22d 100644 --- a/llvm/test/Transforms/LowerGuardIntrinsic/basic.ll +++ b/llvm/test/Transforms/LowerGuardIntrinsic/basic.ll @@ -60,3 +60,15 @@ define i32 @f_zero_args(i1* %c_ptr) { ; CHECK: guarded: ; CHECK-NEXT: ret i32 500 } + +define i8 @f_with_make_implicit_md(i32* %ptr) { +; CHECK-LABEL: @f_with_make_implicit_md( +; CHECK: br i1 %notNull, label %guarded, label %deopt, !make.implicit !0 +; CHECK: deopt: +; CHECK-NEXT: %deoptcall = call i8 (...) @llvm.experimental.deoptimize.i8(i32 1) [ "deopt"(i32 1) ] +; CHECK-NEXT: ret i8 %deoptcall + + %notNull = icmp ne i32* %ptr, null + call void(i1, ...) @llvm.experimental.guard(i1 %notNull, i32 1) [ "deopt"(i32 1) ], !make.implicit !{} + ret i8 5 +}