From: Gabe Black <gblack@eecs.umich.edu>
Date: Wed, 5 Aug 2009 09:57:47 +0000 (-0700)
Subject: X86: Fix sign extension when doing an arithmetic shift right by 0.
X-Git-Tag: Calvin_Submission~182
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=860f0f835097e884d15069af22efec9c8d766b4e;p=gem5.git

X86: Fix sign extension when doing an arithmetic shift right by 0.
---

diff --git a/src/arch/x86/isa/microops/regop.isa b/src/arch/x86/isa/microops/regop.isa
index e86e9f00a..4d4079f5f 100644
--- a/src/arch/x86/isa/microops/regop.isa
+++ b/src/arch/x86/isa/microops/regop.isa
@@ -700,7 +700,7 @@ let {{
             // Because what happens to the bits shift -in- on a right shift
             // is not defined in the C/C++ standard, we have to sign extend
             // them manually to be sure.
-            uint64_t arithMask =
+            uint64_t arithMask = (shiftAmt == 0) ? 0 :
                 -bits(psrc1, dataSize * 8 - 1) << (dataSize * 8 - shiftAmt);
             DestReg = merge(DestReg, (psrc1 >> shiftAmt) | arithMask, dataSize);
             '''