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[LoopUnrollRuntime] Remove strict assert about VMap requirement

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When unrolling under multiple exits which is under off-by-default option,
the assert that checks for VMap entry in loop exit values is too strong.
(assert if VMap entry did not exist, the value should be a
constant). However, values derived from
constants or from values outside loop, does not have a VMap entry too.

Removed the assert and added a testcase showcasing the property for
non-constant values.

llvm-svn: 307542
This commit is contained in:
Anna Thomas
2017-07-10 15:29:38 +00:00
parent 8bd2cca391
commit 70ffd65ca9
2 changed files with 45 additions and 5 deletions
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7
llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
View File

@@ -710,11 +710,10 @@ bool llvm::UnrollRuntimeLoopRemainder(Loop *L, unsigned Count,
// node.
for (unsigned i =0; i < oldNumOperands; i++){
Value *newVal = VMap[Phi->getIncomingValue(i)];
if (!newVal) {
assert(isa<Constant>(Phi->getIncomingValue(i)) &&
"VMap should exist for all values except constants!");
// newVal can be a constant or derived from values outside the loop, and
// hence need not have a VMap value.
if (!newVal)
newVal = Phi->getIncomingValue(i);
}
Phi->addIncoming(newVal,
cast<BasicBlock>(VMap[Phi->getIncomingBlock(i)]));
}

43
llvm/test/Transforms/LoopUnroll/runtime-loop-multiple-exits.ll
View File

@@ -1,9 +1,10 @@
; RUN: opt < %s -loop-unroll -unroll-runtime=true -unroll-runtime-epilog=true -unroll-runtime-multi-exit=true -verify-dom-info -verify-loop-info -S | FileCheck %s -check-prefix=EPILOG-NO-IC
; RUN: opt < %s -loop-unroll -unroll-runtime=true -unroll-runtime-epilog=true -unroll-runtime-multi-exit=true -verify-dom-info -verify-loop-info -instcombine -S | FileCheck %s -check-prefix=EPILOG
; RUN: opt < %s -loop-unroll -unroll-runtime -unroll-count=2 -unroll-runtime-epilog=true -unroll-runtime-multi-exit=true -verify-dom-info -verify-loop-info -instcombine
; RUN: opt < %s -loop-unroll -unroll-runtime=true -unroll-runtime-epilog=false -unroll-runtime-multi-exit=true -verify-dom-info -verify-loop-info -instcombine -S | FileCheck %s -check-prefix=PROLOG
; RUN: opt < %s -loop-unroll -unroll-runtime -unroll-runtime-epilog=false -unroll-count=2 -unroll-runtime-multi-exit=true -verify-dom-info -verify-loop-info -instcombine
; the second and fourth RUNs generate an epilog/prolog remainder block for all the test
; the third and fifth RUNs generate an epilog/prolog remainder block for all the test
; cases below (it does not generate a loop).
; test with three exiting and three exit blocks.
@@ -393,3 +394,43 @@ exit_true:
exit_false:
ret i32 %addx
}
; test when value in exit block does not have VMap.
define i32 @test7(i32 %arg, i32 %arg1, i32 %arg2) {
; EPILOG-NO-IC: test7(
; EPILOG-NO-IC: loopexit1.loopexit:
; EPILOG-NO-IC-NEXT: %sext3.ph = phi i32 [ %shft, %header ], [ %shft, %latch ], [ %shft, %latch.1 ], [ %shft, %latch.2 ], [ %shft, %latch.3 ], [ %shft, %latch.4 ], [ %shft, %latch.5 ], [ %shft, %latch.6 ]
; EPILOG-NO-IC-NEXT: br label %loopexit1
; EPILOG-NO-IC: loopexit1.loopexit1:
; EPILOG-NO-IC-NEXT: %sext3.ph2 = phi i32 [ %shft, %header.epil ]
; EPILOG-NO-IC-NEXT: br label %loopexit1
; EPILOG-NO-IC: loopexit1:
; EPILOG-NO-IC-NEXT: %sext3 = phi i32 [ %sext3.ph, %loopexit1.loopexit ], [ %sext3.ph2, %loopexit1.loopexit1 ]
bb:
%tmp = icmp slt i32 undef, 2
%sext = sext i32 undef to i64
%shft = ashr exact i32 %arg, 16
br i1 %tmp, label %loopexit2, label %preheader
preheader: ; preds = %bb2
br label %header
header: ; preds = %latch, %preheader
%tmp6 = phi i64 [ 1, %preheader ], [ %add, %latch ]
br i1 false, label %loopexit1, label %latch
latch: ; preds = %header
%add = add nuw nsw i64 %tmp6, 1
%tmp9 = icmp slt i64 %add, %sext
br i1 %tmp9, label %header, label %latchexit
latchexit: ; preds = %latch
unreachable
loopexit2: ; preds = %bb2
ret i32 %shft
loopexit1: ; preds = %header
%sext3 = phi i32 [ %shft, %header ]
ret i32 %sext3
}