b90a8d385e
This deals with a corner case of LCSSA phi nodes in the outer loop latch
block: the loop was in LCSSA form, some transformations can come along
(e.g. unswitch) and create an empty block:
BB4:
br label %BB5
BB5:
%old.cond.lcssa = phi i16 [ %cond, %BB4 ]
br outer.header
Interchange then brings it in LCSSA form again and we get:
BB4:
%new.cond.lcssa = phi i16 [ %cond, %BB3 ]
br label %BB5
BB5:
%old.cond.lcssa = phi i16 [ %new.cond.lcssa, %BB4 ]
Which means that we have a chain of LCSSA phi nodes from %new.cond.lcssa
to %old.cond.lcssa. The problem is that interchange can reoder blocks
BB4 and BB5 placing the use before the def if we don't check this. The
solution is to simplify lcssa phis, and remove them from non-exit blocks
if they are 1-input phi nodes.
Fixes #160068
80 lines
3.3 KiB
LLVM
80 lines
3.3 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
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; RUN: opt < %s -passes=loop-interchange -cache-line-size=64 -verify-dom-info -verify-loop-info -verify-scev -verify-loop-lcssa -S | FileCheck %s
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; This test is checking that blocks outer.body and outer.latch, where outer.body is the exit
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; block of the inner loop and outer.latch the latch of the outer loop, correctly
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; deal with the phi-node use-def chain %new.cond.lcssa -> %old.cond.lcssa. What we expect
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; here is that block outer.latch does not contain a phi node, because it is a single input
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; phi in a non-exit block.
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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define i16 @main(ptr %a) {
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; CHECK-LABEL: define i16 @main(
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; CHECK-SAME: ptr [[A:%.*]]) {
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; CHECK-NEXT: [[ENTRY:.*:]]
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; CHECK-NEXT: br label %[[INNER_HEADER_PREHEADER:.*]]
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; CHECK: [[OUTER_HEADER_PREHEADER:.*]]:
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; CHECK-NEXT: br label %[[OUTER_HEADER:.*]]
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; CHECK: [[OUTER_HEADER]]:
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; CHECK-NEXT: [[I:%.*]] = phi i64 [ [[I_NEXT:%.*]], %[[OUTER_LATCH:.*]] ], [ 1, %[[OUTER_HEADER_PREHEADER]] ]
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; CHECK-NEXT: br label %[[INNER_HEADER_SPLIT:.*]]
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; CHECK: [[INNER_HEADER_PREHEADER]]:
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; CHECK-NEXT: br label %[[INNER_HEADER:.*]]
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; CHECK: [[INNER_HEADER]]:
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; CHECK-NEXT: [[J:%.*]] = phi i16 [ [[TMP1:%.*]], %[[INNER_LATCH_SPLIT:.*]] ], [ 0, %[[INNER_HEADER_PREHEADER]] ]
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; CHECK-NEXT: br label %[[OUTER_HEADER_PREHEADER]]
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; CHECK: [[INNER_HEADER_SPLIT]]:
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; CHECK-NEXT: [[ARRAYIDX_US_US:%.*]] = getelementptr i16, ptr [[A]], i16 [[J]]
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; CHECK-NEXT: [[TMP0:%.*]] = load i16, ptr [[ARRAYIDX_US_US]], align 1
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; CHECK-NEXT: [[COND:%.*]] = select i1 false, i16 0, i16 0
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; CHECK-NEXT: br label %[[INNER_LATCH:.*]]
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; CHECK: [[INNER_LATCH]]:
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; CHECK-NEXT: [[J_NEXT:%.*]] = add i16 [[J]], 1
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; CHECK-NEXT: br label %[[OUTER_BODY:.*]]
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; CHECK: [[INNER_LATCH_SPLIT]]:
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; CHECK-NEXT: [[NEW_COND_LCSSA:%.*]] = phi i16 [ [[COND]], %[[OUTER_LATCH]] ]
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; CHECK-NEXT: [[TMP1]] = add i16 [[J]], 1
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; CHECK-NEXT: br i1 true, label %[[EXIT:.*]], label %[[INNER_HEADER]]
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; CHECK: [[OUTER_BODY]]:
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; CHECK-NEXT: br label %[[OUTER_LATCH]]
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; CHECK: [[OUTER_LATCH]]:
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; CHECK-NEXT: [[I_NEXT]] = add i64 [[I]], 1
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; CHECK-NEXT: [[CMP286_US:%.*]] = icmp ugt i64 [[I]], 0
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; CHECK-NEXT: br i1 [[CMP286_US]], label %[[OUTER_HEADER]], label %[[INNER_LATCH_SPLIT]]
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; CHECK: [[EXIT]]:
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; CHECK-NEXT: [[OLD_COND_LCSSA_LCSSA:%.*]] = phi i16 [ [[NEW_COND_LCSSA]], %[[INNER_LATCH_SPLIT]] ]
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; CHECK-NEXT: ret i16 [[OLD_COND_LCSSA_LCSSA]]
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;
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entry:
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br label %outer.header
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outer.header:
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%i = phi i64 [ 1, %entry ], [ %i.next, %outer.latch ]
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br label %inner.header
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inner.header:
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%j = phi i16 [ 0, %outer.header ], [ %j.next, %inner.latch ]
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%arrayidx.us.us = getelementptr i16, ptr %a, i16 %j
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%0 = load i16, ptr %arrayidx.us.us, align 1
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%cond = select i1 false, i16 0, i16 0
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br label %inner.latch
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inner.latch:
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%j.next = add i16 %j, 1
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br i1 true, label %outer.body, label %inner.header
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outer.body:
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%new.cond.lcssa = phi i16 [ %cond, %inner.latch ]
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br label %outer.latch
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outer.latch:
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%old.cond.lcssa = phi i16 [ %new.cond.lcssa, %outer.body ]
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%i.next = add i64 %i, 1
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%cmp286.us = icmp ugt i64 %i, 0
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br i1 %cmp286.us, label %outer.header, label %exit
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exit:
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ret i16 %old.cond.lcssa
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}
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