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clang-p2996/llvm/test/Transforms/IRCE/range_intersect_miscompile.ll
Fedor Sergeev 194a407bda [New PM][IRCE] port of Inductive Range Check Elimination pass to the new pass manager 
There are two nontrivial details here:
* Loop structure update interface is quite different with new pass manager,
  so the code to add new loops was factored out

* BranchProbabilityInfo is not a loop analysis, so it can not be just getResult'ed from
  within the loop pass. It cant even be queried through getCachedResult as LoopCanonicalization
  sequence (e.g. LoopSimplify) might invalidate BPI results.

  Complete solution for BPI will likely take some time to discuss and figure out,
  so for now this was partially solved by making BPI optional in IRCE
  (skipping a couple of profitability checks if it is absent).

Most of the IRCE tests got their corresponding new-pass-manager variant enabled.
Only two of them depend on BPI, both marked with TODO, to be turned on when BPI
starts being available for loop passes.

Reviewers: chandlerc, mkazantsev, sanjoy, asbirlea
Reviewed By: mkazantsev
Differential Revision: https://reviews.llvm.org/D43795

llvm-svn: 327619
2018-03-15 11:01:19 +00:00

288 lines
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; RUN: opt -verify-loop-info -irce-print-changed-loops -irce -S < %s 2>&1 | FileCheck %s
; RUN: opt -verify-loop-info -irce-print-changed-loops -passes='require<branch-prob>,loop(irce)' -S < %s 2>&1 | FileCheck %s
; CHECK-LABEL: irce: in function test_01: constrained Loop at depth 1 containing:
; CHECK-LABEL: irce: in function test_02: constrained Loop at depth 1 containing:
; CHECK-LABEL: irce: in function test_03: constrained Loop at depth 1 containing:
; CHECK-LABEL: irce: in function test_04: constrained Loop at depth 1 containing:
; CHECK-LABEL: irce: in function test_05: constrained Loop at depth 1 containing:
; This test used to demonstrate a miscompile: the outer loop's IV iterates in
; range of [2, 400) and the range check is done against value 331. Due to a bug
; in range intersection IRCE manages to eliminate the range check without
; inserting a postloop, which is incorrect. We treat the range of this test as
; an unsigned range and are able to intersect ranges correctly and insert a
; postloop.
define void @test_01() {
; CHECK-LABEL: test_01
; CHECK-NOT: preloop
; CHECK: range_check_block: ; preds = %inner_loop
; CHECK-NEXT: %range_check = icmp slt i32 %iv, 331
; CHECK-NEXT: br i1 true, label %loop_latch
; CHECK: loop_latch:
; CHECK-NEXT: %iv_next = add i32 %iv, 1
; CHECK-NEXT: %loop_cond = icmp ult i32 %iv_next, 400
; CHECK-NEXT: [[COND:%[^ ]+]] = icmp ult i32 %iv_next, 331
; CHECK-NEXT: br i1 [[COND]], label %loop_header, label %main.exit.selector
; CHECK: main.exit.selector: ; preds = %loop_latch
; CHECK-NEXT: %iv_next.lcssa = phi i32 [ %iv_next, %loop_latch ]
; CHECK-NEXT: %iv.lcssa = phi i32 [ %iv, %loop_latch ]
; CHECK-NEXT: [[MES_COND:%[^ ]+]] = icmp ult i32 %iv_next.lcssa, 400
; CHECK-NEXT: br i1 [[MES_COND]], label %main.pseudo.exit, label %exit
; CHECK: loop_latch.postloop: ; preds = %range_check_block.postloop
; CHECK-NEXT: %iv_next.postloop = add i32 %iv.postloop, 1
; CHECK-NEXT: %loop_cond.postloop = icmp ult i32 %iv_next.postloop, 400
; CHECK-NEXT: br i1 %loop_cond.postloop, label %loop_header.postloop, label %exit.loopexit
entry:
br label %loop_header
loop_header: ; preds = %loop_latch, %entry
%iv = phi i32 [ 2, %entry ], [ %iv_next, %loop_latch ]
%iv.prev = phi i32 [ 1, %entry ], [ %iv, %loop_latch ]
%tmp2 = icmp sgt i32 %iv.prev, -1
br i1 %tmp2, label %loop_header.split.us, label %exit
loop_header.split.us: ; preds = %loop_header
br label %inner_loop
inner_loop: ; preds = %inner_loop, %loop_header.split.us
%inner_iv = phi i32 [ 1, %loop_header.split.us ], [ %inner_iv_next, %inner_loop ]
%inner_iv_next = add nuw nsw i32 %inner_iv, 1
%inner_cond = icmp ult i32 %inner_iv_next, 31
br i1 %inner_cond, label %inner_loop, label %range_check_block
exit: ; preds = %loop_latch, %loop_header
ret void
range_check_block: ; preds = %inner_loop
%range_check = icmp slt i32 %iv, 331
br i1 %range_check, label %loop_latch, label %deopt
loop_latch: ; preds = %range_check_block
%iv_next = add i32 %iv, 1
%loop_cond = icmp ult i32 %iv_next, 400
br i1 %loop_cond, label %loop_header, label %exit
deopt: ; preds = %range_check_block
ret void
}
; Similar to test_01, but here the range check is done against 450. No postloop
; is required.
define void @test_02() {
; CHECK-LABEL: test_02
; CHECK-NOT: preloop
; CHECK-NOT: postloop
; CHECK: range_check_block: ; preds = %inner_loop
; CHECK-NEXT: %range_check = icmp slt i32 %iv, 450
; CHECK-NEXT: br i1 true, label %loop_latch
; CHECK: loop_latch: ; preds = %range_check_block
; CHECK-NEXT: %iv_next = add i32 %iv, 1
; CHECK-NEXT: %loop_cond = icmp ult i32 %iv_next, 400
; CHECK-NEXT: br i1 %loop_cond, label %loop_header, label %exit
entry:
br label %loop_header
loop_header: ; preds = %loop_latch, %entry
%iv = phi i32 [ 2, %entry ], [ %iv_next, %loop_latch ]
%iv.prev = phi i32 [ 1, %entry ], [ %iv, %loop_latch ]
%tmp2 = icmp sgt i32 %iv.prev, -1
br i1 %tmp2, label %loop_header.split.us, label %exit
loop_header.split.us: ; preds = %loop_header
br label %inner_loop
inner_loop: ; preds = %inner_loop, %loop_header.split.us
%inner_iv = phi i32 [ 1, %loop_header.split.us ], [ %inner_iv_next, %inner_loop ]
%inner_iv_next = add nuw nsw i32 %inner_iv, 1
%inner_cond = icmp ult i32 %inner_iv_next, 31
br i1 %inner_cond, label %inner_loop, label %range_check_block
exit: ; preds = %loop_latch, %loop_header
ret void
range_check_block: ; preds = %inner_loop
%range_check = icmp slt i32 %iv, 450
br i1 %range_check, label %loop_latch, label %deopt
loop_latch: ; preds = %range_check_block
%iv_next = add i32 %iv, 1
%loop_cond = icmp ult i32 %iv_next, 400
br i1 %loop_cond, label %loop_header, label %exit
deopt: ; preds = %range_check_block
ret void
}
; Range check is made against 0, so the safe iteration range is empty. IRCE
; should not apply to the inner loop. The condition %tmp2 can be eliminated.
define void @test_03() {
; CHECK-LABEL: test_03
; CHECK-NOT: preloop
; CHECK-NOT: postloop
; CHECK: %tmp2 = icmp sgt i32 %iv.prev, -1
; CHECK-NEXT: br i1 true, label %loop_header.split.us, label %exit
; CHECK: range_check_block:
; CHECK-NEXT: %range_check = icmp slt i32 %iv, 0
; CHECK-NEXT: br i1 %range_check, label %loop_latch, label %deopt
entry:
br label %loop_header
loop_header: ; preds = %loop_latch, %entry
%iv = phi i32 [ 2, %entry ], [ %iv_next, %loop_latch ]
%iv.prev = phi i32 [ 1, %entry ], [ %iv, %loop_latch ]
%tmp2 = icmp sgt i32 %iv.prev, -1
br i1 %tmp2, label %loop_header.split.us, label %exit
loop_header.split.us: ; preds = %loop_header
br label %inner_loop
inner_loop: ; preds = %inner_loop, %loop_header.split.us
%inner_iv = phi i32 [ 1, %loop_header.split.us ], [ %inner_iv_next, %inner_loop ]
%inner_iv_next = add nuw nsw i32 %inner_iv, 1
%inner_cond = icmp ult i32 %inner_iv_next, 31
br i1 %inner_cond, label %inner_loop, label %range_check_block
exit: ; preds = %loop_latch, %loop_header
ret void
range_check_block: ; preds = %inner_loop
%range_check = icmp slt i32 %iv, 0
br i1 %range_check, label %loop_latch, label %deopt
loop_latch: ; preds = %range_check_block
%iv_next = add i32 %iv, 1
%loop_cond = icmp ult i32 %iv_next, 400
br i1 %loop_cond, label %loop_header, label %exit
deopt: ; preds = %range_check_block
ret void
}
; We do not know whether %n is positive or negative, so we prohibit IRCE in
; order to avoid incorrect intersection of signed and unsigned ranges.
; The condition %tmp2 can be eliminated.
define void @test_04(i32* %p) {
; CHECK-LABEL: test_04
; CHECK-NOT: preloop
; CHECK-NOT: postloop
; CHECK: %tmp2 = icmp sgt i32 %iv.prev, -1
; CHECK-NEXT: br i1 true, label %loop_header.split.us, label %exit
; CHECK: range_check_block:
; CHECK-NEXT: %range_check = icmp slt i32 %iv, %n
; CHECK-NEXT: br i1 %range_check, label %loop_latch, label %deopt
entry:
%n = load i32, i32* %p
br label %loop_header
loop_header: ; preds = %loop_latch, %entry
%iv = phi i32 [ 2, %entry ], [ %iv_next, %loop_latch ]
%iv.prev = phi i32 [ 1, %entry ], [ %iv, %loop_latch ]
%tmp2 = icmp sgt i32 %iv.prev, -1
br i1 %tmp2, label %loop_header.split.us, label %exit
loop_header.split.us: ; preds = %loop_header
br label %inner_loop
inner_loop: ; preds = %inner_loop, %loop_header.split.us
%inner_iv = phi i32 [ 1, %loop_header.split.us ], [ %inner_iv_next, %inner_loop ]
%inner_iv_next = add nuw nsw i32 %inner_iv, 1
%inner_cond = icmp ult i32 %inner_iv_next, 31
br i1 %inner_cond, label %inner_loop, label %range_check_block
exit: ; preds = %loop_latch, %loop_header
ret void
range_check_block: ; preds = %inner_loop
%range_check = icmp slt i32 %iv, %n
br i1 %range_check, label %loop_latch, label %deopt
loop_latch: ; preds = %range_check_block
%iv_next = add i32 %iv, 1
%loop_cond = icmp ult i32 %iv_next, 400
br i1 %loop_cond, label %loop_header, label %exit
deopt: ; preds = %range_check_block
ret void
}
; Same as test_04, but range guarantees that %n is positive. So we can safely
; intersect ranges (with insertion of postloop).
define void @test_05(i32* %p) {
; CHECK-LABEL: test_05
; CHECK-NOT: preloop
; CHECK: entry:
; CHECK-NEXT: %n = load i32, i32* %p, !range !6
; CHECK-NEXT: [[CMP_1:%[^ ]+]] = icmp ugt i32 %n, 2
; CHECK-NEXT: %exit.mainloop.at = select i1 [[CMP_1]], i32 %n, i32 2
; CHECK-NEXT: [[CMP_2:%[^ ]+]] = icmp ult i32 2, %exit.mainloop.at
; CHECK-NEXT: br i1 [[CMP_2]], label %loop_header.preheader, label %main.pseudo.exit
; CHECK: range_check_block: ; preds = %inner_loop
; CHECK-NEXT: %range_check = icmp slt i32 %iv, %n
; CHECK-NEXT: br i1 true, label %loop_latch, label %deopt.loopexit2
; CHECK: loop_latch: ; preds = %range_check_block
; CHECK-NEXT: %iv_next = add i32 %iv, 1
; CHECK-NEXT: %loop_cond = icmp ult i32 %iv_next, 400
; CHECK-NEXT: [[COND:%[^ ]+]] = icmp ult i32 %iv_next, %exit.mainloop.at
; CHECK-NEXT: br i1 [[COND]], label %loop_header, label %main.exit.selector
; CHECK: main.exit.selector: ; preds = %loop_latch
; CHECK-NEXT: %iv_next.lcssa = phi i32 [ %iv_next, %loop_latch ]
; CHECK-NEXT: %iv.lcssa = phi i32 [ %iv, %loop_latch ]
; CHECK-NEXT: [[MES_COND:%[^ ]+]] = icmp ult i32 %iv_next.lcssa, 400
; CHECK-NEXT: br i1 [[MES_COND]], label %main.pseudo.exit, label %exit
; CHECK: loop_latch.postloop: ; preds = %range_check_block.postloop
; CHECK-NEXT: %iv_next.postloop = add i32 %iv.postloop, 1
; CHECK-NEXT: %loop_cond.postloop = icmp ult i32 %iv_next.postloop, 400
; CHECK-NEXT: br i1 %loop_cond.postloop, label %loop_header.postloop, label %exit.loopexit
entry:
%n = load i32, i32* %p, !range !0
br label %loop_header
loop_header: ; preds = %loop_latch, %entry
%iv = phi i32 [ 2, %entry ], [ %iv_next, %loop_latch ]
%iv.prev = phi i32 [ 1, %entry ], [ %iv, %loop_latch ]
%tmp2 = icmp sgt i32 %iv.prev, -1
br i1 %tmp2, label %loop_header.split.us, label %exit
loop_header.split.us: ; preds = %loop_header
br label %inner_loop
inner_loop: ; preds = %inner_loop, %loop_header.split.us
%inner_iv = phi i32 [ 1, %loop_header.split.us ], [ %inner_iv_next, %inner_loop ]
%inner_iv_next = add nuw nsw i32 %inner_iv, 1
%inner_cond = icmp ult i32 %inner_iv_next, 31
br i1 %inner_cond, label %inner_loop, label %range_check_block
exit: ; preds = %loop_latch, %loop_header
ret void
range_check_block: ; preds = %inner_loop
%range_check = icmp slt i32 %iv, %n
br i1 %range_check, label %loop_latch, label %deopt
loop_latch: ; preds = %range_check_block
%iv_next = add i32 %iv, 1
%loop_cond = icmp ult i32 %iv_next, 400
br i1 %loop_cond, label %loop_header, label %exit
deopt: ; preds = %range_check_block
ret void
}
!0 = !{i32 0, i32 50}
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