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526a418eb7
The most common use case is when eliminating redundant range checks in an example like the following: c = a[i+1] + a[i]; Note that all the smarts of the transform (the implication engine) is already in ValueTracking and is tested directly through InstructionSimplify. Differential Revision: http://reviews.llvm.org/D13040 llvm-svn: 251596
82 lines
1.9 KiB
LLVM
82 lines
1.9 KiB
LLVM
; RUN: opt %s -S -simplifycfg | FileCheck %s
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; Check for when one branch implies the value of a successors conditional and
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; it's not simply the same conditional repeated.
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define void @test(i32 %length.i, i32 %i) {
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; CHECK-LABEL: @test
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%iplus1 = add nsw i32 %i, 1
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%var29 = icmp slt i32 %iplus1, %length.i
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; CHECK: br i1 %var29, label %in_bounds, label %out_of_bounds
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br i1 %var29, label %next, label %out_of_bounds
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next:
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; CHECK-LABEL: in_bounds:
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; CHECK-NEXT: ret void
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%var30 = icmp slt i32 %i, %length.i
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br i1 %var30, label %in_bounds, label %out_of_bounds2
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in_bounds:
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ret void
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out_of_bounds:
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call void @foo(i64 0)
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unreachable
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out_of_bounds2:
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call void @foo(i64 1)
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unreachable
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}
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; If the add is not nsw, it's not safe to use the fact about i+1 to imply the
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; i condition since it could have overflowed.
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define void @test_neg(i32 %length.i, i32 %i) {
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; CHECK-LABEL: @test_neg
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%iplus1 = add i32 %i, 1
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%var29 = icmp slt i32 %iplus1, %length.i
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; CHECK: br i1 %var29, label %next, label %out_of_bounds
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br i1 %var29, label %next, label %out_of_bounds
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next:
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%var30 = icmp slt i32 %i, %length.i
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; CHECK: br i1 %var30, label %in_bounds, label %out_of_bounds2
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br i1 %var30, label %in_bounds, label %out_of_bounds2
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in_bounds:
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ret void
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out_of_bounds:
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call void @foo(i64 0)
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unreachable
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out_of_bounds2:
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call void @foo(i64 1)
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unreachable
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}
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define void @test2(i32 %length.i, i32 %i) {
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; CHECK-LABEL: @test2
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%iplus100 = add nsw i32 %i, 100
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%var29 = icmp slt i32 %iplus100, %length.i
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; CHECK: br i1 %var29, label %in_bounds, label %out_of_bounds
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br i1 %var29, label %next, label %out_of_bounds
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next:
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%var30 = icmp slt i32 %i, %length.i
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br i1 %var30, label %in_bounds, label %out_of_bounds2
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in_bounds:
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ret void
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out_of_bounds:
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call void @foo(i64 0)
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unreachable
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out_of_bounds2:
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call void @foo(i64 1)
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unreachable
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}
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declare void @foo(i64)
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