[PATCH] D43631: [MC] Don't crash on modulo by zero (PR35650)

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon created this revision.
RKSimon added reviewers: davide, grosbach, echristo, rafael.
Herald added subscribers: arichardson, emaste.

Extension to https://reviews.llvm.org/D12776, handle modulo by zero in the same way we handle divide by zero.


Repository:
  rL LLVM

https://reviews.llvm.org/D43631

Files:
  lib/MC/MCExpr.cpp
  test/MC/ELF/div-by-zero.s


Index: test/MC/ELF/div-by-zero.s
===================================================================
--- test/MC/ELF/div-by-zero.s
+++ test/MC/ELF/div-by-zero.s
@@ -4,3 +4,6 @@
 
 // CHECK: expected relocatable expression
 .int 1/0
+
+// CHECK: expected relocatable expression
+.int 2%0
Index: lib/MC/MCExpr.cpp
===================================================================
--- lib/MC/MCExpr.cpp
+++ lib/MC/MCExpr.cpp
@@ -754,15 +754,19 @@
     case MCBinaryExpr::Add:  Result = LHS + RHS; break;
     case MCBinaryExpr::And:  Result = LHS & RHS; break;
     case MCBinaryExpr::Div:
+    case MCBinaryExpr::Mod:
       // Handle division by zero. gas just emits a warning and keeps going,
       // we try to be stricter.
       // FIXME: Currently the caller of this function has no way to understand
       // we're bailing out because of 'division by zero'. Therefore, it will
       // emit a 'expected relocatable expression' error. It would be nice to
       // change this code to emit a better diagnostic.
       if (RHS == 0)
         return false;
-      Result = LHS / RHS;
+      if (ABE->getOpcode() == MCBinaryExpr::Div)
+        Result = LHS / RHS;
+      else
+        Result = LHS % RHS;
       break;
     case MCBinaryExpr::EQ:   Result = LHS == RHS; break;
     case MCBinaryExpr::GT:   Result = LHS > RHS; break;
@@ -772,7 +776,6 @@
     case MCBinaryExpr::LShr: Result = uint64_t(LHS) >> uint64_t(RHS); break;
     case MCBinaryExpr::LT:   Result = LHS < RHS; break;
     case MCBinaryExpr::LTE:  Result = LHS <= RHS; break;
-    case MCBinaryExpr::Mod:  Result = LHS % RHS; break;
     case MCBinaryExpr::Mul:  Result = LHS * RHS; break;
     case MCBinaryExpr::NE:   Result = LHS != RHS; break;
     case MCBinaryExpr::Or:   Result = LHS | RHS; break;


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