660403940c
There are a number of issues with the current code for converting ule -> ult (etc) predicates for comparisons controlling finite loops: * It sets nowrap flags, which may only hold for that particular comparison, not globally. (PR60944) * It doesn't check that the RHS is invariant. (I'm not sure this can cause practical issues independently of the previous point.) * It runs before simplifications that may be more profitable. (PR54191) This patch moves the handling for this into computeExitLimitFromICmp(), because it is somewhat tightly coupled with assumptions in that code, and addresses the aforementioned issues. Fixes https://github.com/llvm/llvm-project/issues/60944. Fixes https://github.com/llvm/llvm-project/issues/54191. Differential Revision: https://reviews.llvm.org/D145510
56 lines
1.8 KiB
LLVM
56 lines
1.8 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
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; RUN: opt -S -passes=indvars < %s | FileCheck %s
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@x = global i32 0
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; %loop2 is never entered and we cannot derive any fact about %iv from it.
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define i32 @main(i32 %iv.start, i32 %arg2) mustprogress {
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; CHECK-LABEL: define i32 @main
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; CHECK-SAME: (i32 [[IV_START:%.*]], i32 [[ARG2:%.*]]) #[[ATTR0:[0-9]+]] {
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br label [[LOOP:%.*]]
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; CHECK: loop:
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; CHECK-NEXT: [[IV:%.*]] = phi i32 [ [[IV_NEXT:%.*]], [[LOOP_LATCH:%.*]] ], [ [[IV_START]], [[ENTRY:%.*]] ]
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; CHECK-NEXT: br i1 false, label [[LOOP2_PREHEADER:%.*]], label [[LOOP_LATCH]]
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; CHECK: loop2.preheader:
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; CHECK-NEXT: br label [[LOOP2:%.*]]
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; CHECK: loop2:
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; CHECK-NEXT: br i1 true, label [[LOOP2_EXIT:%.*]], label [[LOOP2]]
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; CHECK: loop2.exit:
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; CHECK-NEXT: br label [[LOOP_LATCH]]
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; CHECK: loop.latch:
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; CHECK-NEXT: [[IV_NEXT]] = sdiv i32 [[ARG2]], [[IV]]
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; CHECK-NEXT: [[CMP2:%.*]] = icmp eq i32 [[IV]], -1
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; CHECK-NEXT: br i1 [[CMP2]], label [[LOOP_EXIT:%.*]], label [[LOOP]]
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; CHECK: loop.exit:
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; CHECK-NEXT: [[IV_NEXT_LCSSA:%.*]] = phi i32 [ [[IV_NEXT]], [[LOOP_LATCH]] ]
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; CHECK-NEXT: ret i32 [[IV_NEXT_LCSSA]]
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;
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entry:
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br label %loop
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loop:
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%iv = phi i32 [ %iv.next, %loop.latch ], [ %iv.start, %entry ]
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br i1 false, label %loop2.preheader, label %loop.latch
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loop2.preheader:
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br label %loop2
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loop2:
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%x = load i32, ptr @x, align 4
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%cmp1 = icmp ult i32 %iv, %x
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br i1 %cmp1, label %loop2.exit, label %loop2
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loop2.exit:
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br label %loop.latch
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loop.latch:
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%iv.next = sdiv i32 %arg2, %iv
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%cmp2 = icmp eq i32 %iv, -1
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br i1 %cmp2, label %loop.exit, label %loop
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loop.exit:
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%iv.next.lcssa = phi i32 [ %iv.next, %loop.latch ]
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ret i32 %iv.next.lcssa
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}
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