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llvm-mirror/test/Transforms/LoopUnroll/unroll-header-exiting-with-phis.ll
Philip Reames a4f9bca98e Do actual DCE in LoopUnroll (try 4)
Turns out simplifyLoopIVs sometimes returns a non-dead instruction in it's DeadInsts out param.  I had done a bit of NFC cleanup which was only NFC if simplifyLoopIVs obeyed it's documentation.  I'm simplfy dropping that part of the change.

Commit message from try 3:

Recommitting after fixing a bug found post commit. Amusingly, try 1 had been correct, and by reverting to incorporate last minute review feedback, I introduce the bug. Oops. :)

Original commit message:

The problem was that recursively deleting an instruction can delete instructions beyond the current iterator (via a dead phi), thus invalidating iteration. Test case added in LoopUnroll/dce.ll to cover this case.

LoopUnroll does a limited DCE pass after unrolling, but if you have a chain of dead instructions, it only deletes the last one. Improve the code to recursively delete all trivially dead instructions.

Differential Revision: https://reviews.llvm.org/D102511
2021-05-19 10:25:31 -07:00

99 lines
4.0 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -S -loop-unroll -unroll-allow-partial | FileCheck %s
; The phi which acts as input to func should not be undef. It should
; have its loop-carried value (the load in for.cond) replaced accordingly
; after unrolling the loop.
define i16 @full_unroll(i16* %A) {
; CHECK-LABEL: @full_unroll(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[FOR_COND:%.*]]
; CHECK: for.cond:
; CHECK-NEXT: br label [[FOR_COND_CLEANUP3:%.*]]
; CHECK: for.cond.cleanup:
; CHECK-NEXT: [[DOTLCSSA10_LCSSA:%.*]] = phi i16 [ [[TMP2_2:%.*]], [[FOR_COND_CLEANUP3_2:%.*]] ]
; CHECK-NEXT: [[TMP3:%.*]] = call i16 @func(i16 [[DOTLCSSA10_LCSSA]])
; CHECK-NEXT: ret i16 0
; CHECK: for.cond.cleanup3:
; CHECK-NEXT: br label [[FOR_COND_CLEANUP3_1:%.*]]
; CHECK: for.cond.cleanup3.1:
; CHECK-NEXT: [[PTR_2:%.*]] = getelementptr inbounds i16, i16* [[A:%.*]], i64 2
; CHECK-NEXT: [[TMP2_2]] = load i16, i16* [[PTR_2]], align 2
; CHECK-NEXT: br label [[FOR_COND_CLEANUP3_2]]
; CHECK: for.cond.cleanup3.2:
; CHECK-NEXT: br i1 false, label [[FOR_COND_CLEANUP3_3:%.*]], label [[FOR_COND_CLEANUP:%.*]]
; CHECK: for.cond.cleanup3.3:
; CHECK-NEXT: unreachable
;
entry:
br label %for.cond
for.cond: ; preds = %for.cond.cleanup3, %entry
%.lcssa10 = phi i16 [ 123, %entry ], [ %.lcssa, %for.cond.cleanup3 ]
%i.0 = phi i64 [ 0, %entry ], [ %inc9, %for.cond.cleanup3 ]
%ptr = getelementptr inbounds i16, i16* %A, i64 %i.0
%tmp2 = load i16, i16* %ptr
%cmp = icmp ult i64 %i.0, 3
br i1 %cmp, label %for.cond.cleanup3, label %for.cond.cleanup
for.cond.cleanup: ; preds = %for.cond
%.lcssa10.lcssa = phi i16 [ %.lcssa10, %for.cond ]
%tmp3 = call i16 (i16) @func(i16 %.lcssa10.lcssa)
ret i16 0
for.cond.cleanup3: ; preds = %for.cond
%.lcssa = phi i16 [ %tmp2, %for.cond ]
%inc9 = add i64 %i.0, 1
br label %for.cond
}
define i16 @partial_unroll(i16* %A) {
; CHECK-LABEL: @partial_unroll(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[FOR_COND:%.*]]
; CHECK: for.cond:
; CHECK-NEXT: [[I_0:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INC9_2:%.*]], [[FOR_COND_CLEANUP3_2:%.*]] ]
; CHECK-NEXT: br label [[FOR_COND_CLEANUP3:%.*]]
; CHECK: for.cond.cleanup:
; CHECK-NEXT: [[DOTLCSSA10_LCSSA:%.*]] = phi i16 [ [[TMP2_1:%.*]], [[FOR_COND_CLEANUP3_1:%.*]] ]
; CHECK-NEXT: [[TMP3:%.*]] = call i16 @func(i16 [[DOTLCSSA10_LCSSA]])
; CHECK-NEXT: ret i16 0
; CHECK: for.cond.cleanup3:
; CHECK-NEXT: [[INC9:%.*]] = add nuw nsw i64 [[I_0]], 1
; CHECK-NEXT: [[PTR_1:%.*]] = getelementptr inbounds i16, i16* [[A:%.*]], i64 [[INC9]]
; CHECK-NEXT: [[TMP2_1]] = load i16, i16* [[PTR_1]], align 2
; CHECK-NEXT: br label [[FOR_COND_CLEANUP3_1]]
; CHECK: for.cond.cleanup3.1:
; CHECK-NEXT: [[INC9_1:%.*]] = add nuw nsw i64 [[INC9]], 1
; CHECK-NEXT: [[CMP_2:%.*]] = icmp ult i64 [[INC9_1]], 200
; CHECK-NEXT: br i1 [[CMP_2]], label [[FOR_COND_CLEANUP3_2]], label [[FOR_COND_CLEANUP:%.*]]
; CHECK: for.cond.cleanup3.2:
; CHECK-NEXT: [[INC9_2]] = add nuw nsw i64 [[INC9_1]], 1
; CHECK-NEXT: br label [[FOR_COND]]
;
entry:
br label %for.cond
for.cond: ; preds = %for.cond.cleanup3, %entry
%.lcssa10 = phi i16 [ 123, %entry ], [ %.lcssa, %for.cond.cleanup3 ]
%i.0 = phi i64 [ 0, %entry ], [ %inc9, %for.cond.cleanup3 ]
%ptr = getelementptr inbounds i16, i16* %A, i64 %i.0
%tmp2 = load i16, i16* %ptr
%cmp = icmp ult i64 %i.0, 200
br i1 %cmp, label %for.cond.cleanup3, label %for.cond.cleanup
for.cond.cleanup: ; preds = %for.cond
%.lcssa10.lcssa = phi i16 [ %.lcssa10, %for.cond ]
%tmp3 = call i16 (i16) @func(i16 %.lcssa10.lcssa)
ret i16 0
for.cond.cleanup3: ; preds = %for.cond
%.lcssa = phi i16 [ %tmp2, %for.cond ]
%inc9 = add i64 %i.0, 1
br label %for.cond
}
declare i16 @func(i16)