[llvm] r306287 - [SystemZ] Add a check against zero before calling getTestUnderMaskCond()

[Jonas Paulsson via llvm-commits]

Author: jonpa
Date: Mon Jun 26 06:38:27 2017
New Revision: 306287

URL: http://llvm.org/viewvc/llvm-project?rev=306287&view=rev
Log:
[SystemZ]  Add a check against zero before calling getTestUnderMaskCond()

Csmith discovered that this function can be called with a zero argument,
in which case an assert for this triggered.

This patch also adds a guard before the other call to this function since
it was missing, although the test only covers the case where it was
discovered.

Reduced test case attached as CodeGen/SystemZ/int-cmp-54.ll.

Review: Ulrich Weigand

Added:
    llvm/trunk/test/CodeGen/SystemZ/int-cmp-54.ll
Modified:
    llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp

Modified: llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp?rev=306287&r1=306286&r2=306287&view=diff
==============================================================================
--- llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp Mon Jun 26 06:38:27 2017
@@ -2054,6 +2054,7 @@ static void adjustForTestUnderMask(Selec
   if (NewC.ICmpType != SystemZICMP::SignedOnly &&
       NewC.Op0.getOpcode() == ISD::SHL &&
       isSimpleShift(NewC.Op0, ShiftVal) &&
+      (MaskVal >> ShiftVal != 0) &&
       (NewCCMask = getTestUnderMaskCond(BitSize, NewC.CCMask,
                                         MaskVal >> ShiftVal,
                                         CmpVal >> ShiftVal,
@@ -2063,6 +2064,7 @@ static void adjustForTestUnderMask(Selec
   } else if (NewC.ICmpType != SystemZICMP::SignedOnly &&
              NewC.Op0.getOpcode() == ISD::SRL &&
              isSimpleShift(NewC.Op0, ShiftVal) &&
+             (MaskVal << ShiftVal != 0) &&
              (NewCCMask = getTestUnderMaskCond(BitSize, NewC.CCMask,
                                                MaskVal << ShiftVal,
                                                CmpVal << ShiftVal,

Added: llvm/trunk/test/CodeGen/SystemZ/int-cmp-54.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/SystemZ/int-cmp-54.ll?rev=306287&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/SystemZ/int-cmp-54.ll (added)
+++ llvm/trunk/test/CodeGen/SystemZ/int-cmp-54.ll Mon Jun 26 06:38:27 2017
@@ -0,0 +1,20 @@
+; Check that custom handling of SETCC does not crash
+;
+; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z13
+
+ at g_39 = external global [4 x i8], align 2
+ at g_2166 = external global <{ i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i32 }>, align 8
+
+; Function Attrs: nounwind
+define void @main() local_unnamed_addr #0 {
+  %1 = load volatile i88, i88* bitcast (<{ i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i32 }>* @g_2166 to i88*), align 8
+  %2 = lshr i88 %1, 87
+  %3 = trunc i88 %2 to i64
+  %4 = icmp sgt i64 %3, 9293
+  %5 = zext i1 %4 to i32
+  %6 = lshr i32 %5, 0
+  %7 = shl i32 %6, 6
+  %8 = trunc i32 %7 to i8
+  store i8 %8, i8* getelementptr inbounds ([4 x i8], [4 x i8]* @g_39, i64 0, i64 1), align 1
+  unreachable
+}