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clang-p2996/llvm/test/Transforms/ConstraintElimination/range_checks.ll
Florian Hahn 13ffde316a [ConstraintElim] Remove dead compares after simplification. 
Remove compares after replacing all uses. Cleaning dead compares can
enable additional simplifications when adjusting the position of the
pass slightly. In particular, it seems like the additional dead
instructions may prevent SimplifyCFG performing some folds.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D158760
2023-08-24 22:12:57 +01:00

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5.9 KiB
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -passes=constraint-elimination -S %s | FileCheck %s
; Here we can remove range check because:
; length >= min_length (from entry)
; idx < min_length (from in_bounds check)
; therefore, idx < length is trivially true.
define i32 @test_01(ptr %p, ptr %array, i32 %min_length) {
; CHECK-LABEL: @test_01(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
; CHECK-NEXT: [[ELEM_PTR:%.*]] = getelementptr i32, ptr [[P:%.*]], i32 [[IV]]
; CHECK-NEXT: [[IDX:%.*]] = load i32, ptr [[ELEM_PTR]], align 4
; CHECK-NEXT: [[IN_BOUNDS:%.*]] = icmp ult i32 [[IDX]], [[MIN_LENGTH:%.*]]
; CHECK-NEXT: br i1 [[IN_BOUNDS]], label [[RANGE_CHECK_BLOCK:%.*]], label [[OUT_OF_BOUNDS:%.*]]
; CHECK: range_check_block:
; CHECK-NEXT: br i1 true, label [[BACKEDGE]], label [[RANGE_CHECK_FAILED:%.*]]
; CHECK: backedge:
; CHECK-NEXT: [[ARR_PTR:%.*]] = getelementptr i32, ptr [[ARRAY:%.*]], i32 [[IDX]]
; CHECK-NEXT: store i32 [[IV]], ptr [[ARR_PTR]], align 4
; CHECK-NEXT: [[IV_NEXT]] = add i32 [[IV]], 1
; CHECK-NEXT: [[LOOP_COND:%.*]] = call i1 @cond()
; CHECK-NEXT: br i1 [[LOOP_COND]], label [[LOOP]], label [[EXIT:%.*]]
; CHECK: exit:
; CHECK-NEXT: [[IV_LCSSA:%.*]] = phi i32 [ [[IV]], [[BACKEDGE]] ]
; CHECK-NEXT: ret i32 [[IV_LCSSA]]
; CHECK: out_of_bounds:
; CHECK-NEXT: ret i32 -1
; CHECK: range_check_failed:
; CHECK-NEXT: [[IV_LCSSA_RC:%.*]] = phi i32 [ [[IV]], [[RANGE_CHECK_BLOCK]] ]
; CHECK-NEXT: call void @failed_range_check(i32 [[IV_LCSSA_RC]])
; CHECK-NEXT: unreachable
;
entry:
br label %loop
loop: ; preds = %backedge, %entry
%iv = phi i32 [ 0, %entry ], [ %iv.next, %backedge ]
%elem_ptr = getelementptr i32, ptr %p, i32 %iv
%idx = load i32, ptr %elem_ptr, align 4
%in_bounds = icmp ult i32 %idx, %min_length
br i1 %in_bounds, label %range_check_block, label %out_of_bounds
range_check_block: ; preds = %loop
%range_check = icmp ult i32 %idx, %min_length
br i1 %range_check, label %backedge, label %range_check_failed
backedge: ; preds = %range_check_block
%arr_ptr = getelementptr i32, ptr %array, i32 %idx
store i32 %iv, ptr %arr_ptr, align 4
%iv.next = add i32 %iv, 1
%loop_cond = call i1 @cond()
br i1 %loop_cond, label %loop, label %exit
exit: ; preds = %backedge
%iv.lcssa = phi i32 [ %iv, %backedge ]
ret i32 %iv.lcssa
out_of_bounds: ; preds = %loop
ret i32 -1
range_check_failed: ; preds = %range_check_block
%iv.lcssa.rc = phi i32 [ %iv, %range_check_block ]
call void @failed_range_check(i32 %iv.lcssa.rc)
unreachable
}
define i32 @test_02(ptr %p, ptr %array, i32 %length, i32 %min_length) {
; CHECK-LABEL: @test_02(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[LENGTH_CHECK:%.*]] = icmp uge i32 [[LENGTH:%.*]], [[MIN_LENGTH:%.*]]
; CHECK-NEXT: br i1 [[LENGTH_CHECK]], label [[LOOP:%.*]], label [[FAILED:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
; CHECK-NEXT: [[ELEM_PTR:%.*]] = getelementptr i32, ptr [[P:%.*]], i32 [[IV]]
; CHECK-NEXT: [[IDX:%.*]] = load i32, ptr [[ELEM_PTR]], align 4
; CHECK-NEXT: [[IN_BOUNDS:%.*]] = icmp ult i32 [[IDX]], [[MIN_LENGTH]]
; CHECK-NEXT: br i1 [[IN_BOUNDS]], label [[RANGE_CHECK_BLOCK:%.*]], label [[OUT_OF_BOUNDS:%.*]]
; CHECK: range_check_block:
; CHECK-NEXT: br i1 true, label [[BACKEDGE]], label [[RANGE_CHECK_FAILED:%.*]]
; CHECK: backedge:
; CHECK-NEXT: [[ARR_PTR:%.*]] = getelementptr i32, ptr [[ARRAY:%.*]], i32 [[IDX]]
; CHECK-NEXT: store i32 [[IV]], ptr [[ARR_PTR]], align 4
; CHECK-NEXT: [[IV_NEXT]] = add i32 [[IV]], 1
; CHECK-NEXT: [[LOOP_COND:%.*]] = call i1 @cond()
; CHECK-NEXT: br i1 [[LOOP_COND]], label [[LOOP]], label [[EXIT:%.*]]
; CHECK: exit:
; CHECK-NEXT: [[IV_LCSSA:%.*]] = phi i32 [ [[IV]], [[BACKEDGE]] ]
; CHECK-NEXT: ret i32 [[IV_LCSSA]]
; CHECK: failed:
; CHECK-NEXT: unreachable
; CHECK: out_of_bounds:
; CHECK-NEXT: ret i32 -1
; CHECK: range_check_failed:
; CHECK-NEXT: [[IV_LCSSA_RC:%.*]] = phi i32 [ [[IV]], [[RANGE_CHECK_BLOCK]] ]
; CHECK-NEXT: call void @failed_range_check(i32 [[IV_LCSSA_RC]])
; CHECK-NEXT: unreachable
;
entry:
%length_check = icmp uge i32 %length, %min_length
br i1 %length_check, label %loop, label %failed
loop: ; preds = %backedge, %entry
%iv = phi i32 [ 0, %entry ], [ %iv.next, %backedge ]
%elem_ptr = getelementptr i32, ptr %p, i32 %iv
%idx = load i32, ptr %elem_ptr, align 4
%in_bounds = icmp ult i32 %idx, %min_length
br i1 %in_bounds, label %range_check_block, label %out_of_bounds
range_check_block: ; preds = %loop
%range_check = icmp ult i32 %idx, %length
br i1 %range_check, label %backedge, label %range_check_failed
backedge: ; preds = %range_check_block
%arr_ptr = getelementptr i32, ptr %array, i32 %idx
store i32 %iv, ptr %arr_ptr, align 4
%iv.next = add i32 %iv, 1
%loop_cond = call i1 @cond()
br i1 %loop_cond, label %loop, label %exit
exit: ; preds = %backedge
%iv.lcssa = phi i32 [ %iv, %backedge ]
ret i32 %iv.lcssa
failed: ; preds = %entry
unreachable
out_of_bounds: ; preds = %loop
ret i32 -1
range_check_failed: ; preds = %range_check_block
%iv.lcssa.rc = phi i32 [ %iv, %range_check_block ]
call void @failed_range_check(i32 %iv.lcssa.rc)
unreachable
}
declare i1 @cond()
declare void @failed_range_check(i32)
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