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clang-p2996/llvm/test/Transforms/IRCE/unsigned_comparisons_ugt.ll
Max Kazantsev 9ac7021a25 [IRCE] Fix intersection between signed and unsigned ranges 
IRCE for unsigned latch conditions was temporarily disabled by rL314881. The motivating
example contained an unsigned latch condition and a signed range check. One of the safe
iteration ranges was `[1, SINT_MAX + 1]`. Its right border was incorrectly interpreted as a negative
value in `IntersectRange` function, this lead to a miscompile under which we deleted a range check
without inserting a postloop where it was needed.

This patch brings back IRCE for unsigned latch conditions. Now we treat range intersection more
carefully. If the latch condition was unsigned, we only try to consider a range check for deletion if:
1. The range check is also unsigned, or
2. Safe iteration range of the range check lies within `[0, SINT_MAX]`.
The same is done for signed latch.

Values from `[0, SINT_MAX]` are unambiguous, these values are non-negative under any interpretation,
and all values of a range intersected with such range are also non-negative.

We also use signed/unsigned min/max functions for range intersection depending on type of the
latch condition.

Differential Revision: https://reviews.llvm.org/D38581

llvm-svn: 316552
2017-10-25 06:47:39 +00:00

264 lines
9.3 KiB
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; RUN: opt -verify-loop-info -irce-print-changed-loops -irce -S < %s 2>&1 | FileCheck %s
; CHECK: irce: in function test_01: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK: irce: in function test_02: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK: irce: in function test_03: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK: irce: in function test_04: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK-NOT: irce: in function test_05: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK: irce: in function test_06: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; UGT condition for increasing loop.
define void @test_01(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_01(
; CHECK: entry:
; CHECK-NEXT: %exit.mainloop.at = load i32, i32* %a_len_ptr, !range !0
; CHECK-NEXT: [[COND:%[^ ]+]] = icmp ult i32 0, %exit.mainloop.at
; CHECK-NEXT: br i1 [[COND]], label %loop.preheader, label %main.pseudo.exit
; CHECK: loop:
; CHECK-NEXT: %idx = phi i32 [ %idx.next, %in.bounds ], [ 0, %loop.preheader ]
; CHECK-NEXT: %idx.next = add nuw nsw i32 %idx, 1
; CHECK-NEXT: %abc = icmp ult i32 %idx, %exit.mainloop.at
; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1
; CHECK-NOT: loop.preloop:
; CHECK: loop.postloop:
; CHECK-NEXT: %idx.postloop = phi i32 [ %idx.copy, %postloop ], [ %idx.next.postloop, %in.bounds.postloop ]
; CHECK-NEXT: %idx.next.postloop = add nuw nsw i32 %idx.postloop, 1
; CHECK-NEXT: %abc.postloop = icmp ult i32 %idx.postloop, %exit.mainloop.at
; CHECK-NEXT: br i1 %abc.postloop, label %in.bounds.postloop, label %out.of.bounds.loopexit
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 0, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add nsw nuw i32 %idx, 1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ugt i32 %idx.next, 100
br i1 %next, label %exit, label %loop
out.of.bounds:
ret void
exit:
ret void
}
; UGT condition for decreasing loop.
define void @test_02(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_02(
; CHECK: entry:
; CHECK-NEXT: %len = load i32, i32* %a_len_ptr, !range !0
; CHECK-NEXT: [[COND1:%[^ ]+]] = icmp ugt i32 %len, 1
; CHECK-NEXT: %umax = select i1 [[COND1]], i32 %len, i32 1
; CHECK-NEXT: %exit.preloop.at = add i32 %umax, -1
; CHECK-NEXT: [[COND2:%[^ ]+]] = icmp ugt i32 100, %exit.preloop.at
; CHECK-NEXT: br i1 [[COND2]], label %loop.preloop.preheader, label %preloop.pseudo.exit
; CHECK: mainloop:
; CHECK-NEXT: br label %loop
; CHECK: loop:
; CHECK-NEXT: %idx = phi i32 [ %idx.preloop.copy, %mainloop ], [ %idx.next, %in.bounds ]
; CHECK-NEXT: %idx.next = add i32 %idx, -1
; CHECK-NEXT: %abc = icmp ult i32 %idx, %len
; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1
; CHECK-NOT: loop.postloop:
; CHECK: loop.preloop:
; CHECK-NEXT: %idx.preloop = phi i32 [ %idx.next.preloop, %in.bounds.preloop ], [ 100, %loop.preloop.preheader ]
; CHECK-NEXT: %idx.next.preloop = add i32 %idx.preloop, -1
; CHECK-NEXT: %abc.preloop = icmp ult i32 %idx.preloop, %len
; CHECK-NEXT: br i1 %abc.preloop, label %in.bounds.preloop, label %out.of.bounds.loopexit
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 100, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add i32 %idx, -1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ugt i32 %idx.next, 0
br i1 %next, label %loop, label %exit
out.of.bounds:
ret void
exit:
ret void
}
; Check SINT_MAX + 1, test is similar to test_01.
define void @test_03(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_03(
; CHECK: entry:
; CHECK-NEXT: %exit.mainloop.at = load i32, i32* %a_len_ptr, !range !0
; CHECK-NEXT: [[COND:%[^ ]+]] = icmp ult i32 0, %exit.mainloop.at
; CHECK-NEXT: br i1 [[COND]], label %loop.preheader, label %main.pseudo.exit
; CHECK: loop:
; CHECK-NEXT: %idx = phi i32 [ %idx.next, %in.bounds ], [ 0, %loop.preheader ]
; CHECK-NEXT: %idx.next = add nuw nsw i32 %idx, 1
; CHECK-NEXT: %abc = icmp ult i32 %idx, %exit.mainloop.at
; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1
; CHECK-NOT: loop.preloop:
; CHECK: loop.postloop:
; CHECK-NEXT: %idx.postloop = phi i32 [ %idx.copy, %postloop ], [ %idx.next.postloop, %in.bounds.postloop ]
; CHECK-NEXT: %idx.next.postloop = add nuw nsw i32 %idx.postloop, 1
; CHECK-NEXT: %abc.postloop = icmp ult i32 %idx.postloop, %exit.mainloop.at
; CHECK-NEXT: br i1 %abc.postloop, label %in.bounds.postloop, label %out.of.bounds.loopexit
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 0, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add nsw nuw i32 %idx, 1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ugt i32 %idx.next, 2147483648
br i1 %next, label %exit, label %loop
out.of.bounds:
ret void
exit:
ret void
}
; Check SINT_MAX + 1, test is similar to test_02.
define void @test_04(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_04(
; CHECK: entry:
; CHECK-NEXT: %len = load i32, i32* %a_len_ptr, !range !0
; CHECK-NEXT: [[COND1:%[^ ]+]] = icmp ugt i32 %len, 1
; CHECK-NEXT: %umax = select i1 [[COND1]], i32 %len, i32 1
; CHECK-NEXT: %exit.preloop.at = add i32 %umax, -1
; CHECK-NEXT: [[COND2:%[^ ]+]] = icmp ugt i32 -2147483648, %exit.preloop.at
; CHECK-NEXT: br i1 [[COND2]], label %loop.preloop.preheader, label %preloop.pseudo.exit
; CHECK: mainloop:
; CHECK-NEXT: br label %loop
; CHECK: loop:
; CHECK-NEXT: %idx = phi i32 [ %idx.preloop.copy, %mainloop ], [ %idx.next, %in.bounds ]
; CHECK-NEXT: %idx.next = add i32 %idx, -1
; CHECK-NEXT: %abc = icmp ult i32 %idx, %len
; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1
; CHECK-NOT: loop.postloop:
; CHECK: loop.preloop:
; CHECK-NEXT: %idx.preloop = phi i32 [ %idx.next.preloop, %in.bounds.preloop ], [ -2147483648, %loop.preloop.preheader ]
; CHECK-NEXT: %idx.next.preloop = add i32 %idx.preloop, -1
; CHECK-NEXT: %abc.preloop = icmp ult i32 %idx.preloop, %len
; CHECK-NEXT: br i1 %abc.preloop, label %in.bounds.preloop, label %out.of.bounds.loopexit
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 2147483648, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add i32 %idx, -1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ugt i32 %idx.next, 0
br i1 %next, label %loop, label %exit
out.of.bounds:
ret void
exit:
ret void
}
; Increasing loop, UINT_MAX. Negative test: we cannot add 1 to UINT_MAX.
define void @test_05(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_05(
; CHECK-NOT: loop.preloop:
; CHECK-NOT: loop.postloop:
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 0, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add nsw nuw i32 %idx, 1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ugt i32 %idx.next, 4294967295
br i1 %next, label %exit, label %loop
out.of.bounds:
ret void
exit:
ret void
}
; Decreasing loop, UINT_MAX. Positive test.
define void @test_06(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_06(
; CHECK: mainloop:
; CHECK-NEXT: br label %loop
; CHECK: loop:
; CHECK-NEXT: %idx = phi i32 [ %idx.preloop.copy, %mainloop ], [ %idx.next, %in.bounds ]
; CHECK-NEXT: %idx.next = add nuw i32 %idx, -1
; CHECK-NEXT: %abc = icmp ult i32 %idx, %len
; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1
; CHECK-NOT: loop.postloop:
; CHECK: loop.preloop:
; CHECK-NEXT: %idx.preloop = phi i32 [ %idx.next.preloop, %in.bounds.preloop ], [ -1, %loop.preloop.preheader ]
; CHECK-NEXT: %idx.next.preloop = add nuw i32 %idx.preloop, -1
; CHECK-NEXT: %abc.preloop = icmp ult i32 %idx.preloop, %len
; CHECK-NEXT: br i1 %abc.preloop, label %in.bounds.preloop, label %out.of.bounds.loopexit
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 4294967295, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add nuw i32 %idx, -1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ugt i32 %idx.next, 0
br i1 %next, label %loop, label %exit
out.of.bounds:
ret void
exit:
ret void
}
!0 = !{i32 0, i32 50}
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