[MCParser] Add warning for zero-size .fill

[jacobly]

Summary

Adding an early return for a 0 size avoids this assertion:

llvm-mc: llvm/lib/MC/MCStreamer.cpp:135: virtual void llvm::MCStreamer::emitIntValue(uint64_t, unsigned int): Assertion `1 <= Size && Size <= 8 && "Invalid size"' failed.

[jdoerfert]

test case missing.

[arsenm]

llvm/lib/MC/MCParser/AsmParser.cpp

3357–3364

Could you just have one message with the value instead

[jacobly]

Improve warning messages.

[jacobly]

llvm/lib/MC/MCParser/AsmParser.cpp

3357–3364

Good idea.

[jacobly]

Fix typo.

[jacobly]

ping

llvm/lib/MC/MCParser/AsmParser.cpp

if (parseOptionalToken(AsmToken::Comma)) {
       ExprLoc = getTok().getLoc();
       if (parseAbsoluteExpression(FillExpr))
         return true;
     }
   }
   if (parseEOL())
     return true;
 
-  if (FillSize < 0) {
-    Warning(SizeLoc, "'.fill' directive with negative size has no effect");
+  if (FillSize <= 0) {
+    Warning(SizeLoc, "'.fill' directive with a size of '" + Twine(FillSize) +
+                         "' has no effect");
     return false;
   }
   if (FillSize > 8) {
-    Warning(SizeLoc, "'.fill' directive with size greater than 8 has been truncated to 8");
+    Warning(SizeLoc, "'.fill' directive with size of '" + Twine(FillSize) +
+                         "' has been truncated to 8");
     FillSize = 8;
   }
 
   if (!isUInt<32>(FillExpr) && FillSize > 4)
     Warning(ExprLoc, "'.fill' directive pattern has been truncated to 32-bits");
 
   getStreamer().emitFill(*NumValues, FillSize, FillExpr, NumValuesLoc);
 

llvm/test/MC/AsmParser/directive_fill.s

 
 # CHECK: TEST5
 # CHECK: .fill 4, 3, 0x2
 TEST5:
   .fill 4, 3, 2
 
 # CHECK: TEST6
 # CHECK: .fill 1, 8, 0x2
-# CHECK-WARNINGS: '.fill' directive with size greater than 8 has been truncated to 8
+# CHECK-WARNINGS: '.fill' directive with size of '9' has been truncated to 8
 TEST6:
   .fill 1, 9, 2
 
 # CHECK: TEST7
 # CHECK: .fill 1, 8, 0x0
 # CHECK-WARNINGS: '.fill' directive pattern has been truncated to 32-bits
 TEST7:
   .fill 1, 8, 1<<32
 
 # CHECK: TEST8
 # CHECK: .fill -1, 8, 0x1
 # OBJ-ERRS: '.fill' directive with negative repeat count has no effect
 TEST8:
   .fill -1, 8, 1
 
-# CHECK-WARNINGS: '.fill' directive with negative size has no effect
+# CHECK-WARNINGS: '.fill' directive with a size of '-1' has no effect
 TEST9:
   .fill 1, -1, 1
 
 # CHECK: TEST10
 # CHECK: .fill 1, 3, 0x12345678
 TEST10:
   .fill 1, 3, 0x12345678
 
TEST12:
   .fill TEST11 - TEST12, 4, 0x12345678
 
 # CHECK: TEST13
 # CHECK: .fill (TEST11-TEST12)+i, 4, 0x12345678
 # OBJ-ERRS: [[@LINE+2]]:8: error: expected assembly-time absolute expression
 TEST13:
   .fill TEST11 - TEST12+i, 4, 0x12345678
 
+# CHECK-WARNINGS: '.fill' directive with a size of '0' has no effect
+TEST14:
+  .fill 1, 0