[LLVMbugs] [Bug 4254] New: ocaml 3.11.0 miscompiled, bugpoint says -instcombine is to blame

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=4254

           Summary: ocaml 3.11.0 miscompiled, bugpoint says -instcombine is
                    to blame
           Product: new-bugs
           Version: unspecified
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: edwintorok at gmail.com
                CC: llvmbugs at cs.uiuc.edu


Created an attachment (id=3021)
 --> (http://llvm.org/bugs/attachment.cgi?id=3021)
bugpoint-tooptimize.bc

Symptom: the ocamlrun build by clang -O rejects pervasives.mli with a syntax
error, the gcc built one doesn't, and neither does a 'clang' built ocamlrun:
File "../stdlib/pervasives.mli", line 29, characters 0-8:
Error: Syntax error

I've run bugpoint like this:
bugpoint -run-jit -safe-run-llc  -output=good -simplifycfg -domtree
-domfrontier -mem2reg -instcombine -simplifycfg -simplify-libcalls -instcombine
-jump-threading -simplifycfg -domtree -domfrontier -scalarrepl -instcombine
-break-crit-edges -condprop -tailcallelim -simplifycfg -reassociate -domtree
-loops -loopsimplify -domfrontier -lcssa -loop-rotate -licm -lcssa
-loop-unswitch -loop-index-split -instcombine -scalar-evolution -lcssa
-iv-users -indvars -loop-deletion -instcombine -memdep -gvn -memdep -memcpyopt
-sccp -instcombine -break-crit-edges -condprop -domtree -memdep -dse -adce
-simplifycfg -preverify -domtree -verify ocamlrun.bc -Xlinker=-lm
-Xlinker=-lpthread -Xlinker=-ldl -Xlinker=-lcurses --args -- ../boot/ocamlc -g
-warn-error A -nostdlib-nopervasives -c ../stdlib/pervasives.mli

And I got 2 bitcodes: bugpoint-tooptimize.bc, and bugpoint-tonotoptimize.bc.
Bugpoint says -instcombine breaks the program.

Here is what instcombine does:
-       %tmp128 = load i8** @intern_src         ; <i8*> [#uses=1]
-       %arrayidx129 = getelementptr i8* %tmp128, i64 -2                ; <i8*>
[#uses=1]
-       %tmp130 = load i8* %arrayidx129         ; <i8> [#uses=1]
-       %conv131 = zext i8 %tmp130 to i32               ; <i32> [#uses=1]
-       %conv132 = sext i32 %conv131 to i64             ; <i64> [#uses=1]
-       %shl133 = shl i64 %conv132, 56          ; <i64> [#uses=1]
-       %shr134 = ashr i64 %shl133, 56          ; <i64> [#uses=1]
-       %shl135 = shl i64 %shr134, 8            ; <i64> [#uses=1]
-       %tmp136 = load i8** @intern_src         ; <i8*> [#uses=1]
-       %arrayidx137 = getelementptr i8* %tmp136, i64 -1                ; <i8*>
[#uses=1]
+       %tmp130 = load i8* %tmp126              ; <i8> [#uses=1]
+       %conv1322 = zext i8 %tmp130 to i64              ; <i64> [#uses=1]
+       %shl133 = shl i64 %conv1322, 56         ; <i64> [#uses=1]
+       %0 = ashr i64 %shl133, 48               ; <i64> [#uses=1]
+       %arrayidx137 = getelementptr i8* %tmp126, i64 1         ; <i8*>
[#uses=1]
        %tmp138 = load i8* %arrayidx137         ; <i8> [#uses=1]
        %conv139 = zext i8 %tmp138 to i64               ; <i64> [#uses=1]
-       %add140 = add i64 %shl135, %conv139             ; <i64> [#uses=1]
+       %add140 = or i64 %0, %conv139           ; <i64> [#uses=1]
        %shl141 = shl i64 %add140, 1            ; <i64> [#uses=1]
-       %add142 = add i64 %shl141, 1            ; <i64> [#uses=1]
-       store i64 %add142, i64* %v
+       %add1421 = or i64 %shl141, 1            ; <i64> [#uses=1]
+       store i64 %add1421, i64* %v


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