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llvm-6502/test/Transforms/IndVarSimplify/2012-07-17-lftr-undef.ll

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indvars: Linear function test replace should avoid reusing undef. Fixes PR13371: indvars pass incorrectly substitutes 'undef' values. I do not like this fix. It's needed until/unless the meaning of undef changes. It attempts to be complete according to the IR spec, but I don't have much confidence in the implementation given the difficulty testing undefined behavior. Worse, this invalidates some of my hard-fought work on indvars and LSR to optimize pointer induction variables. It results benchmark regressions, which I'll track internally. On x86_64 no LTO I see: -3% huffbench -3% 400.perlbench -8% fhourstones My only suggestion for recovering is to change the meaning of undef. If we could trust an arbitrary instruction to produce a some real value that can be manipulated (e.g. incremented) according to non-undef rules, then this case could be easily handled with SCEV. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160421 91177308-0d34-0410-b5e6-96231b3b80d8
2012-07-18 04:35:10 +00:00
; RUN: opt < %s -indvars -S | FileCheck %s
; PR13371: indvars pass incorrectly substitutes 'undef' values
;
; LFTR should not user %undef as the loop counter.
Update Transforms tests to use CHECK-LABEL for easier debugging. No functionality change. This update was done with the following bash script: find test/Transforms -name "*.ll" | \ while read NAME; do echo "$NAME" if ! grep -q "^; *RUN: *llc" $NAME; then TEMP=`mktemp -t temp` cp $NAME $TEMP sed -n "s/^define [^@]*@\([A-Za-z0-9_]*\)(.*$/\1/p" < $NAME | \ while read FUNC; do sed -i '' "s/;\(.*\)\([A-Za-z0-9_]*\):\( *\)@$FUNC\([( ]*\)\$/;\1\2-LABEL:\3@$FUNC(/g" $TEMP done mv $TEMP $NAME fi done git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186268 91177308-0d34-0410-b5e6-96231b3b80d8
2013-07-14 01:42:54 +00:00
; CHECK-LABEL: @test(
indvars: Linear function test replace should avoid reusing undef. Fixes PR13371: indvars pass incorrectly substitutes 'undef' values. I do not like this fix. It's needed until/unless the meaning of undef changes. It attempts to be complete according to the IR spec, but I don't have much confidence in the implementation given the difficulty testing undefined behavior. Worse, this invalidates some of my hard-fought work on indvars and LSR to optimize pointer induction variables. It results benchmark regressions, which I'll track internally. On x86_64 no LTO I see: -3% huffbench -3% 400.perlbench -8% fhourstones My only suggestion for recovering is to change the meaning of undef. If we could trust an arbitrary instruction to produce a some real value that can be manipulated (e.g. incremented) according to non-undef rules, then this case could be easily handled with SCEV. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160421 91177308-0d34-0410-b5e6-96231b3b80d8
2012-07-18 04:35:10 +00:00
; CHECK-NOT: icmp{{.*}}undef
@.str3 = private constant [6 x i8] c"%lld\0A\00", align 1
declare i32 @printf(i8* noalias nocapture, ...) nounwind
define i64 @test() nounwind {
func_start:
br label %block9
block9: ; preds = %block9,%func_start
%undef = phi i64 [ %next_undef, %block9 ], [ undef, %func_start ]
%iter = phi i64 [ %next_iter, %block9 ], [ 1, %func_start ]
%next_iter = add nsw i64 %iter, 1
%0 = tail call i32 (i8*, ...)* @printf(i8* noalias nocapture getelementptr inbounds ([6 x i8]* @.str3, i64 0, i64 0), i64 %next_iter, i64 %undef)
%next_undef = add nsw i64 %undef, 1
%_tmp_3 = icmp slt i64 %next_iter, 100
br i1 %_tmp_3, label %block9, label %exit
exit: ; preds = %block9
ret i64 0
}
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