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Max Kazantsev 9e73a14fba Re-enable "[IndVars] Canonicalize comparisons between non-negative values and indvars"
The patch was reverted due to a bug. The bug was that if the IV is the 2nd operand of the icmp
instruction, then the "Pred" variable gets swapped and differs from the instruction's predicate.
In this patch we use the original predicate to do the transformation.

Also added a test case that exercises this situation.

Differentian Revision: https://reviews.llvm.org/D35107

llvm-svn: 307477
2017-07-08 17:17:30 +00:00

99 lines
1.8 KiB
LLVM

; RUN: opt -S -indvars < %s | FileCheck %s
; Check that we replace signed comparisons between non-negative values with
; unsigned comparisons if we can.
target datalayout = "n8:16:32:64"
define i32 @test_01(i32 %a, i32 %b, i32* %p) {
; CHECK-LABEL: @test_01(
; CHECK-NOT: icmp slt
; CHECK: %cmp1 = icmp ult i32 %iv, 100
; CHECK: %cmp2 = icmp ult i32 %iv, 100
; CHECK-NOT: %cmp3
; CHECK: %exitcond = icmp ne i32 %iv.next, 1000
entry:
br label %loop.entry
loop.entry:
%iv = phi i32 [ 0, %entry ], [ %iv.next, %loop.be ]
%cmp1 = icmp slt i32 %iv, 100
br i1 %cmp1, label %b1, label %b2
b1:
store i32 %iv, i32* %p
br label %merge
b2:
store i32 %a, i32* %p
br label %merge
merge:
%cmp2 = icmp ult i32 %iv, 100
br i1 %cmp2, label %b3, label %b4
b3:
store i32 %iv, i32* %p
br label %loop.be
b4:
store i32 %b, i32* %p
br label %loop.be
loop.be:
%iv.next = add i32 %iv, 1
%cmp3 = icmp slt i32 %iv.next, 1000
br i1 %cmp3, label %loop.entry, label %exit
exit:
ret i32 %iv
}
define i32 @test_02(i32 %a, i32 %b, i32* %p) {
; CHECK-LABEL: @test_02(
; CHECK-NOT: icmp sgt
; CHECK: %cmp1 = icmp ugt i32 100, %iv
; CHECK: %cmp2 = icmp ugt i32 100, %iv
; CHECK-NOT: %cmp3
; CHECK: %exitcond = icmp ne i32 %iv.next, 1000
entry:
br label %loop.entry
loop.entry:
%iv = phi i32 [ 0, %entry ], [ %iv.next, %loop.be ]
%cmp1 = icmp sgt i32 100, %iv
br i1 %cmp1, label %b1, label %b2
b1:
store i32 %iv, i32* %p
br label %merge
b2:
store i32 %a, i32* %p
br label %merge
merge:
%cmp2 = icmp ugt i32 100, %iv
br i1 %cmp2, label %b3, label %b4
b3:
store i32 %iv, i32* %p
br label %loop.be
b4:
store i32 %b, i32* %p
br label %loop.be
loop.be:
%iv.next = add i32 %iv, 1
%cmp3 = icmp sgt i32 1000, %iv.next
br i1 %cmp3, label %loop.entry, label %exit
exit:
ret i32 %iv
}