ISD::SIGN_EXTEND_INREG added during Legalization and not Legalized

[llvmbot]

Bugzilla Link	2794
Resolution	FIXED
Resolved on	Oct 13, 2008 13:46
Version	unspecified
OS	All
Reporter	LLVM Bugzilla Contributor

Extended Description

LegalizeDAG.cpp adds a ISD::SIGN_EXTEND_INREG node during promotion but doesn't make sure to verify that the resulting DAG is legal for the target.

The fix is:

Index: LegalizeDAG.cpp

--- LegalizeDAG.cpp (revision 56194)
+++ LegalizeDAG.cpp (working copy)
@@ -4670,6 +4670,8 @@
DAG.getValueType(VT));
Tmp2 = DAG.getNode(ISD::SIGN_EXTEND_INREG, NVT, Tmp2,
DAG.getValueType(VT));

•    Tmp1 = LegalizeOp(Tmp1);
  

•    Tmp2 = LegalizeOp(Tmp2);
     break;
   }
  

  }

[llvmbot]

Thanks. Do you have a test case by any chance?

[llvmbot]

LegalizeDAG.cpp adds a ISD::SIGN_EXTEND_INREG node during promotion but doesn't
make sure to verify that the resulting DAG is legal for the target.

The fix is:

Index: LegalizeDAG.cpp

--- LegalizeDAG.cpp (revision 56194)
+++ LegalizeDAG.cpp (working copy)
@@ -4670,6 +4670,8 @@
DAG.getValueType(VT));
Tmp2 = DAG.getNode(ISD::SIGN_EXTEND_INREG, NVT, Tmp2,
DAG.getValueType(VT));

•    Tmp1 = LegalizeOp(Tmp1);
  

•    Tmp2 = LegalizeOp(Tmp2);
     break;
   }
  

  }

Thanks. Do you have a test case by any chance?

No, sorry. This was found in a rather large file and only occurred when optimization was turned on. I wasn't able to create a small test case.

[llvmbot]

Well, is llc crashing? Can you use bugpoint to reduce a test case?

[llvmbot]

Well, is llc crashing? Can you use bugpoint to reduce a test case?

This occurs using my own code generator. I'll try to make a test case that fails with one of the standard LLVM code generators. I need to find one that doesn't support SIGN_EXTEND_INREG, of course.

I get a "Cannot select" assert from my code generator.

By the way, this is the only place in LegalizeDAG.cpp that a SIGN_EXTEND_INREG is introduced that is not followed by a call to LegalizeOp.

[llvmbot]

Well, is llc crashing? Can you use bugpoint to reduce a test case?

This occurs using my own code generator. I'll try to make a test case that
fails with one of the standard LLVM code generators. I need to find one that
doesn't support SIGN_EXTEND_INREG, of course.

I get a "Cannot select" assert from my code generator.

By the way, this is the only place in LegalizeDAG.cpp that a SIGN_EXTEND_INREG
is introduced that is not followed by a call to LegalizeOp.

OK. I have a test case. It fails with (at least) the MIPS code generator.

; ModuleID = 'ofmt.bc'
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-s0:0:64-f80:32:32"
target triple = "mips-elf"

define i32 @​main(i8*) nounwind {
entry:
br label %continue.outer

continue.outer: ; preds = %case4, %entry
%p.0.ph.rec = phi i32 [ 0, %entry ], [ %indvar.next, %case4 ] ; [#uses=2]
%p.0.ph = getelementptr i8* %0, i32 %p.0.ph.rec ; <i8*> [#uses=1]
%1 = load i8* %p.0.ph ; [#uses=1]
switch i8 %1, label %infloop [
i8 0, label %return.split
i8 76, label %case4
i8 108, label %case4
i8 104, label %case4
i8 42, label %case4
]

case4: ; preds = %continue.outer, %continue.outer, %continue.outer, %continue.outer
%indvar.next = add i32 %p.0.ph.rec, 1 ; [#uses=1]
br label %continue.outer

return.split: ; preds = %continue.outer
ret i32 0

infloop: ; preds = %infloop, %continue.outer
br label %infloop
}

Not pretty, but it is as small as I could make it.
Running llc:

[~/ellcc/ellcc] main% llc -march mips ofmt.bc
Cannot yet select: 0xab48654: i32 = sign_extend_inreg 0xab48104, 0xab47ee4
llc[0x8bc7ea2]
llc[0x8bc7fd4]
[0x110400]
/lib/libc.so.6(abort+0x101)[0xa62f91]
llc[0x84d38ea]
llc[0x84d6d92]
llc[0x84d8422]
llc[0x84d8889]
llc[0x84d8a1e]
llc(_ZN4llvm16SelectionDAGISel17CodeGenAndEmitDAGEv+0x8ac)[0x88bdf4a]
llc(_ZN4llvm16SelectionDAGISel16FinishBasicBlockEv+0x1340)[0x88bf59e]
llc(_ZN4llvm16SelectionDAGISel20SelectAllBasicBlocksERNS_8FunctionERNS_15MachineFunctionE+0x51b)[0x88c0a69]
llc(_ZN4llvm16SelectionDAGISel13runOnFunctionERNS_8FunctionE+0x322)[0x88c1388]
llc(_ZN4llvm13FPPassManager13runOnFunctionERNS_8FunctionE+0xfa)[0x8b558e6]
llc(_ZN4llvm23FunctionPassManagerImpl3runERNS_8FunctionE+0x74)[0x8b55e74]
llc(_ZN4llvm19FunctionPassManager3runERNS_8FunctionE+0x89)[0x8b55fcf]
llc(main+0x9b4)[0x83d0358]
/lib/libc.so.6(__libc_start_main+0xe0)[0xa4e390]
llc[0x83ce951]
Abort

After the patch applied:
[/ellcc/ellcc] main% llc -march mips ofmt.bc
[/ellcc/ellcc] main%

"make" in the test directory:

...
=== Summary ===

of expected passes 2736

of expected failures 7

[~/llvm-build/test] main%

[llvmbot]

Thanks. Patch and test case are committed.
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20081013/068406.html