From 8a9a783f2ceb7ba982a62e2fb3f2d089939f6cda Mon Sep 17 00:00:00 2001 From: Hal Finkel Date: Wed, 11 Jan 2017 13:24:24 +0000 Subject: Make processing @llvm.assume more efficient - Add affected values to the assumption cache Here's my second try at making @llvm.assume processing more efficient. My previous attempt, which leveraged operand bundles, r289755, didn't end up working: it did make assume processing more efficient but eliminating the assumption cache made ephemeral value computation too expensive. This is a more-targeted change. We'll keep the assumption cache, but extend it to keep a map of affected values (i.e. values about which an assumption might provide some information) to the corresponding assumption intrinsics. This allows ValueTracking and LVI to find assumptions relevant to the value being queried without scanning all assumptions in the function. The fact that ValueTracking started doing O(number of assumptions in the function) work, for every known-bits query, has become prohibitively expensive in some cases. As discussed during the review, this is a pragmatic fix that, longer term, will likely be replaced by a more-principled solution (perhaps based on an extended SSA form). Differential Revision: https://reviews.llvm.org/D28459 llvm-svn: 291671 --- llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp | 3 +++ 1 file changed, 3 insertions(+) (limited to 'llvm/lib/Transforms') diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp index d51d3687ea3..2ef82ba3ed8 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp @@ -2756,6 +2756,9 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) { if (KnownOne.isAllOnesValue()) return eraseInstFromFunction(*II); + // Update the cache of affected values for this assumption (we might be + // here because we just simplified the condition). + AC.updateAffectedValues(II); break; } case Intrinsic::experimental_gc_relocate: { -- cgit v1.2.3