[llvm] r268148 - [LowerGuardIntrinsics] Keep track of !make.implicit metadata

[Sanjoy Das via llvm-commits]

Author: sanjoy
Date: Fri Apr 29 19:55:59 2016
New Revision: 268148

URL: http://llvm.org/viewvc/llvm-project?rev=268148&view=rev
Log:
[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.

Modified:
    llvm/trunk/docs/LangRef.rst
    llvm/trunk/lib/Transforms/Scalar/LowerGuardIntrinsic.cpp
    llvm/trunk/test/Transforms/LowerGuardIntrinsic/basic.ll

Modified: llvm/trunk/docs/LangRef.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/LangRef.rst?rev=268148&r1=268147&r2=268148&view=diff
==============================================================================
--- llvm/trunk/docs/LangRef.rst (original)
+++ llvm/trunk/docs/LangRef.rst Fri Apr 29 19:55:59 2016
@@ -12375,7 +12375,7 @@ equivalent to:
 
 	define void @llvm.experimental.guard(i1 %pred, <args...>) {
 	  %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(<args...>) [ "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``

Modified: llvm/trunk/lib/Transforms/Scalar/LowerGuardIntrinsic.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LowerGuardIntrinsic.cpp?rev=268148&r1=268147&r2=268148&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LowerGuardIntrinsic.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LowerGuardIntrinsic.cpp Fri Apr 29 19:55:59 2016
@@ -56,6 +56,9 @@ static void MakeGuardControlFlowExplicit
   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}, "");
 

Modified: llvm/trunk/test/Transforms/LowerGuardIntrinsic/basic.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LowerGuardIntrinsic/basic.ll?rev=268148&r1=268147&r2=268148&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LowerGuardIntrinsic/basic.ll (original)
+++ llvm/trunk/test/Transforms/LowerGuardIntrinsic/basic.ll Fri Apr 29 19:55:59 2016
@@ -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
+}