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llvm-project/llvm/test/Transforms/GVNHoist/hoist-pr28933.ll

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[GVNHoist] Factor out reachability to search for anticipable instructions quickly Factor out the reachability such that multiple queries to find reachability of values are fast. This is based on finding the ANTIC points in the CFG which do not change during hoisting. The ANTIC points are basically the dominance-frontiers in the inverse graph. So we introduce a data structure (CHI nodes) to keep track of values flowing out of a basic block. We only do this for values with multiple occurrences in the function as they are the potential hoistable candidates. This patch allows us to hoist instructions to a basic block with >2 successors, as well as deal with infinite loops in a trivial way. Relevant test cases are added to show the functionality as well as regression fixes from PR32821. Regression from previous GVNHoist: We do not hoist fully redundant expressions because fully redundant expressions are already handled by NewGVN Differential Revision: https://reviews.llvm.org/D35918 Reviewers: dberlin, sebpop, gberry, llvm-svn: 313116
2017-09-13 13:28:03 +08:00
; RUN: opt -S -gvn-hoist -verify-memoryssa -newgvn < %s | FileCheck %s
Fix PR 28933 Summary: This fixes PR 28933 by making sure GVNHoist does not try to recreate memory accesses when it has not actually moved them. Reviewers: sebpop Subscribers: llvm-commits, george.burgess.iv Differential Revision: https://reviews.llvm.org/D23411 llvm-svn: 278401
2016-08-12 04:32:43 +08:00
; Check that we end up with one load and one store, in the right order
; CHECK-LABEL: define void @test_it(
; CHECK: store
; CHECK-NOT: store
; CHECK-NOT: load
%rec894.0.1.2.3.12 = type { i16 }
@a = external global %rec894.0.1.2.3.12
define void @test_it() {
bb2:
store i16 undef, i16* getelementptr inbounds (%rec894.0.1.2.3.12, %rec894.0.1.2.3.12* @a, i16 0, i32 0), align 1
%_tmp61 = load i16, i16* getelementptr inbounds (%rec894.0.1.2.3.12, %rec894.0.1.2.3.12* @a, i16 0, i32 0), align 1
store i16 undef, i16* getelementptr inbounds (%rec894.0.1.2.3.12, %rec894.0.1.2.3.12* @a, i16 0, i32 0), align 1
%_tmp92 = load i16, i16* getelementptr inbounds (%rec894.0.1.2.3.12, %rec894.0.1.2.3.12* @a, i16 0, i32 0), align 1
ret void
}