Merge pull request #167 from Prof9/fix-shift-edge-cases

THUMB: Fix negative branches not getting truncated anymore and change…
Kingcom · May 2, 2020 · 5b88a04 · 5b88a04
2 parents 17952fa + 7e4730f
commit 5b88a04
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Showing 2 changed files with 16 additions and 7 deletions.
diff --git a/Archs/ARM/CThumbInstruction.cpp b/Archs/ARM/CThumbInstruction.cpp
@@ -138,15 +138,24 @@ bool CThumbInstruction::Validate()
 			}
 			Vars.Immediate = pos >> 2;
 		}
-
-		if (Vars.ImmediateBitLen != 32)
+
+		if (Opcode.type == THUMB_TYPE1)
+		{
+			int max = (Opcode.flags & THUMB_RIGHTSHIFT_IMMEDIATE) ? 32 : 31;
+			if (Vars.Immediate < 0 || Vars.Immediate > max)
+			{
+				Logger::queueError(Logger::Error, L"Shift amount 0x%02X out of range",Vars.Immediate);
+				return false;
+			}
+		} else if (Vars.ImmediateBitLen != 32)
 		{
-			int max = (1 << Vars.ImmediateBitLen) - ((Opcode.flags & THUMB_RIGHTSHIFT_IMMEDIATE) ? 0 : 1);
+			int max = (1 << Vars.ImmediateBitLen) - 1;
 			if (abs(Vars.Immediate) > max)
 			{
 				Logger::queueError(Logger::Error,L"Immediate value 0x%02X out of range",Vars.Immediate);
 				return false;
 			}
+			Vars.Immediate &= max;
 		}
 	}
 

diff --git a/Tests/ARM/ShiftInvalid/expected.txt b/Tests/ARM/ShiftInvalid/expected.txt
@@ -1,7 +1,7 @@
-ShiftInvalid.asm(5) error: Immediate value 0x20 out of range
-ShiftInvalid.asm(6) error: Immediate value 0x20 out of range
-ShiftInvalid.asm(7) error: Immediate value 0x21 out of range
-ShiftInvalid.asm(8) error: Immediate value 0x21 out of range
+ShiftInvalid.asm(5) error: Shift amount 0x20 out of range
+ShiftInvalid.asm(6) error: Shift amount 0x20 out of range
+ShiftInvalid.asm(7) error: Shift amount 0x21 out of range
+ShiftInvalid.asm(8) error: Shift amount 0x21 out of range
 ShiftInvalid.asm(11) error: Shift amount 0x20 out of range
 ShiftInvalid.asm(12) error: Shift amount 0x20 out of range
 ShiftInvalid.asm(13) error: Shift amount 0x21 out of range