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clang-p2996/llvm/test/Transforms/IndVarSimplify/eliminate-exit.ll
Philip Reames 34495b5533 [IndVars] Use exit count reasoning to discharge obviously untaken exits 
Continue in the spirit of D63618, and use exit count reasoning to prove away loop exits which can not be taken since the backedge taken count of the loop as a whole is provably less than the minimal BE count required to take this particular loop exit.

As demonstrated in the newly added tests, this triggers in a number of cases where IndVars was previously unable to discharge obviously redundant exit tests. And some not so obvious ones.

Differential Revision: https://reviews.llvm.org/D63733

llvm-svn: 365920
2019-07-12 17:05:35 +00:00

190 lines
6.2 KiB
LLVM
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -indvars -S < %s | FileCheck %s
define void @ult(i64 %n, i64 %m) {
; CHECK-LABEL: @ult(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP0:%.*]] = icmp ult i64 [[N:%.*]], [[M:%.*]]
; CHECK-NEXT: br i1 [[CMP0]], label [[LOOP_PREHEADER:%.*]], label [[EXIT:%.*]]
; CHECK: loop.preheader:
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], [[LATCH:%.*]] ], [ 0, [[LOOP_PREHEADER]] ]
; CHECK-NEXT: [[IV_NEXT]] = add i64 [[IV]], 1
; CHECK-NEXT: [[CMP1:%.*]] = icmp ult i64 [[IV]], [[N]]
; CHECK-NEXT: br i1 [[CMP1]], label [[LATCH]], label [[EXIT_LOOPEXIT:%.*]]
; CHECK: latch:
; CHECK-NEXT: call void @side_effect()
; CHECK-NEXT: br i1 true, label [[LOOP]], label [[EXIT_LOOPEXIT]]
; CHECK: exit.loopexit:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret void
;
entry:
%cmp0 = icmp ult i64 %n, %m
br i1 %cmp0, label %loop, label %exit
loop:
%iv = phi i64 [ 0, %entry ], [ %iv.next, %latch ]
%iv.next = add i64 %iv, 1
%cmp1 = icmp ult i64 %iv, %n
br i1 %cmp1, label %latch, label %exit
latch:
call void @side_effect()
%cmp2 = icmp ult i64 %iv, %m
br i1 %cmp2, label %loop, label %exit
exit:
ret void
}
define void @ugt(i64 %n, i64 %m) {
; CHECK-LABEL: @ugt(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP0:%.*]] = icmp ugt i64 [[N:%.*]], [[M:%.*]]
; CHECK-NEXT: br i1 [[CMP0]], label [[LOOP_PREHEADER:%.*]], label [[EXIT:%.*]]
; CHECK: loop.preheader:
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], [[LATCH:%.*]] ], [ 0, [[LOOP_PREHEADER]] ]
; CHECK-NEXT: [[IV_NEXT]] = add i64 [[IV]], 1
; CHECK-NEXT: br i1 true, label [[LATCH]], label [[EXIT_LOOPEXIT:%.*]]
; CHECK: latch:
; CHECK-NEXT: call void @side_effect()
; CHECK-NEXT: [[CMP2:%.*]] = icmp ult i64 [[IV]], [[M]]
; CHECK-NEXT: br i1 [[CMP2]], label [[LOOP]], label [[EXIT_LOOPEXIT]]
; CHECK: exit.loopexit:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret void
;
entry:
%cmp0 = icmp ugt i64 %n, %m
br i1 %cmp0, label %loop, label %exit
loop:
%iv = phi i64 [ 0, %entry ], [ %iv.next, %latch ]
%iv.next = add i64 %iv, 1
%cmp1 = icmp ult i64 %iv, %n
br i1 %cmp1, label %latch, label %exit
latch:
call void @side_effect()
%cmp2 = icmp ult i64 %iv, %m
br i1 %cmp2, label %loop, label %exit
exit:
ret void
}
define void @ule(i64 %n, i64 %m) {
; CHECK-LABEL: @ule(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP0:%.*]] = icmp ule i64 [[N:%.*]], [[M:%.*]]
; CHECK-NEXT: br i1 [[CMP0]], label [[LOOP_PREHEADER:%.*]], label [[EXIT:%.*]]
; CHECK: loop.preheader:
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], [[LATCH:%.*]] ], [ 0, [[LOOP_PREHEADER]] ]
; CHECK-NEXT: [[IV_NEXT]] = add i64 [[IV]], 1
; CHECK-NEXT: [[CMP1:%.*]] = icmp ult i64 [[IV]], [[N]]
; CHECK-NEXT: br i1 [[CMP1]], label [[LATCH]], label [[EXIT_LOOPEXIT:%.*]]
; CHECK: latch:
; CHECK-NEXT: call void @side_effect()
; CHECK-NEXT: [[CMP2:%.*]] = icmp ult i64 [[IV]], [[M]]
; CHECK-NEXT: br i1 [[CMP2]], label [[LOOP]], label [[EXIT_LOOPEXIT]]
; CHECK: exit.loopexit:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret void
;
entry:
%cmp0 = icmp ule i64 %n, %m
br i1 %cmp0, label %loop, label %exit
loop:
%iv = phi i64 [ 0, %entry ], [ %iv.next, %latch ]
%iv.next = add i64 %iv, 1
%cmp1 = icmp ult i64 %iv, %n
br i1 %cmp1, label %latch, label %exit
latch:
call void @side_effect()
%cmp2 = icmp ult i64 %iv, %m
br i1 %cmp2, label %loop, label %exit
exit:
ret void
}
define void @uge(i64 %n, i64 %m) {
; CHECK-LABEL: @uge(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP0:%.*]] = icmp uge i64 [[N:%.*]], [[M:%.*]]
; CHECK-NEXT: br i1 [[CMP0]], label [[LOOP_PREHEADER:%.*]], label [[EXIT:%.*]]
; CHECK: loop.preheader:
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], [[LATCH:%.*]] ], [ 0, [[LOOP_PREHEADER]] ]
; CHECK-NEXT: [[IV_NEXT]] = add i64 [[IV]], 1
; CHECK-NEXT: [[CMP1:%.*]] = icmp ult i64 [[IV]], [[N]]
; CHECK-NEXT: br i1 [[CMP1]], label [[LATCH]], label [[EXIT_LOOPEXIT:%.*]]
; CHECK: latch:
; CHECK-NEXT: call void @side_effect()
; CHECK-NEXT: [[CMP2:%.*]] = icmp ult i64 [[IV]], [[M]]
; CHECK-NEXT: br i1 [[CMP2]], label [[LOOP]], label [[EXIT_LOOPEXIT]]
; CHECK: exit.loopexit:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret void
;
entry:
%cmp0 = icmp uge i64 %n, %m
br i1 %cmp0, label %loop, label %exit
loop:
%iv = phi i64 [ 0, %entry ], [ %iv.next, %latch ]
%iv.next = add i64 %iv, 1
%cmp1 = icmp ult i64 %iv, %n
br i1 %cmp1, label %latch, label %exit
latch:
call void @side_effect()
%cmp2 = icmp ult i64 %iv, %m
br i1 %cmp2, label %loop, label %exit
exit:
ret void
}
define void @ult_const_max(i64 %n) {
; CHECK-LABEL: @ult_const_max(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP0:%.*]] = icmp ult i64 [[N:%.*]], 20
; CHECK-NEXT: br i1 [[CMP0]], label [[LOOP_PREHEADER:%.*]], label [[EXIT:%.*]]
; CHECK: loop.preheader:
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], [[LATCH:%.*]] ], [ 0, [[LOOP_PREHEADER]] ]
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: br i1 true, label [[LATCH]], label [[EXIT_LOOPEXIT:%.*]]
; CHECK: latch:
; CHECK-NEXT: call void @side_effect()
; CHECK-NEXT: [[CMP2:%.*]] = icmp ult i64 [[IV]], [[N]]
; CHECK-NEXT: br i1 [[CMP2]], label [[LOOP]], label [[EXIT_LOOPEXIT]]
; CHECK: exit.loopexit:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret void
;
entry:
%cmp0 = icmp ult i64 %n, 20
br i1 %cmp0, label %loop, label %exit
loop:
%iv = phi i64 [ 0, %entry ], [ %iv.next, %latch ]
%iv.next = add i64 %iv, 1
%udiv = udiv i64 %iv, 10
%cmp1 = icmp ult i64 %udiv, 2
br i1 %cmp1, label %latch, label %exit
latch:
call void @side_effect()
%cmp2 = icmp ult i64 %iv, %n
br i1 %cmp2, label %loop, label %exit
exit:
ret void
}
declare void @side_effect()
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