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llvm-project/llvm/test/Transforms/JumpThreading/assume-edge-dom.ll

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[LVI] Check for @llvm.assume dominating the edge branch When LazyValueInfo uses @llvm.assume intrinsics to provide edge-value constraints, we should check for intrinsics that dominate the edge's branch, not just any potential context instructions. An assumption that dominates the edge's branch represents a truth on that edge. This is specifically useful, for example, if multiple predecessors assume a pointer to be nonnull, allowing us to simplify a later null comparison. The test case, and an initial patch, were provided by Philip Reames. Thanks! llvm-svn: 219688
2014-10-15 00:04:49 +08:00
; RUN: opt -S -jump-threading < %s | FileCheck %s
declare i8* @escape()
declare void @llvm.assume(i1)
define i1 @test1(i1 %cond) {
entry:
br i1 %cond, label %taken, label %not_taken
; CHECK-LABEL: @test1
; CHECK: br i1 %cond, label %no, label %yes
; CHECK: ret i1 true
taken:
%res1 = call i8* @escape()
%a = icmp eq i8* %res1, null
Revert @llvm.assume with operator bundles (r289755-r289757) This creates non-linear behavior in the inliner (see more details in r289755's commit thread). llvm-svn: 290086
2016-12-19 16:22:17 +08:00
tail call void @llvm.assume(i1 %a)
[LVI] Check for @llvm.assume dominating the edge branch When LazyValueInfo uses @llvm.assume intrinsics to provide edge-value constraints, we should check for intrinsics that dominate the edge's branch, not just any potential context instructions. An assumption that dominates the edge's branch represents a truth on that edge. This is specifically useful, for example, if multiple predecessors assume a pointer to be nonnull, allowing us to simplify a later null comparison. The test case, and an initial patch, were provided by Philip Reames. Thanks! llvm-svn: 219688
2014-10-15 00:04:49 +08:00
br label %done
not_taken:
%res2 = call i8* @escape()
%b = icmp ne i8* %res2, null
Revert @llvm.assume with operator bundles (r289755-r289757) This creates non-linear behavior in the inliner (see more details in r289755's commit thread). llvm-svn: 290086
2016-12-19 16:22:17 +08:00
tail call void @llvm.assume(i1 %b)
[LVI] Check for @llvm.assume dominating the edge branch When LazyValueInfo uses @llvm.assume intrinsics to provide edge-value constraints, we should check for intrinsics that dominate the edge's branch, not just any potential context instructions. An assumption that dominates the edge's branch represents a truth on that edge. This is specifically useful, for example, if multiple predecessors assume a pointer to be nonnull, allowing us to simplify a later null comparison. The test case, and an initial patch, were provided by Philip Reames. Thanks! llvm-svn: 219688
2014-10-15 00:04:49 +08:00
br label %done
; An assume that can be used to simplify this comparison dominates each
; predecessor branch (although no assume dominates the cmp itself). Make sure
; this still can be simplified.
done:
%res = phi i8* [ %res1, %taken ], [ %res2, %not_taken ]
%cnd = icmp ne i8* %res, null
br i1 %cnd, label %yes, label %no
yes:
ret i1 true
no:
ret i1 false
}