From: Sandipan Das <sandipan@linux.ibm.com>
Date: Sat, 6 Feb 2021 11:51:45 +0000 (+0530)
Subject: arch-power: Fix disassembly for shift instructions
X-Git-Tag: develop-gem5-snapshot~25
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=b576984bcebe4fc83dd6598823581679c081488e;p=gem5.git

arch-power: Fix disassembly for shift instructions

This fixes disassembly generated for integer shift
instructions based on the type of operand used for
the specifying the shift amount.

Change-Id: I4985334e6eaa9c09ce2d4e79b23e1ae7a9cd28c3
Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
---

diff --git a/src/arch/power/insts/integer.cc b/src/arch/power/insts/integer.cc
index 4c62f37ba..12344b3d9 100644
--- a/src/arch/power/insts/integer.cc
+++ b/src/arch/power/insts/integer.cc
@@ -584,8 +584,21 @@ IntShiftOp::generateDisassembly(
         Addr pc, const Loader::SymbolTable *symtab) const
 {
     std::stringstream ss;
+    bool printSecondSrc = true;
+    bool printShift = false;
 
-    ccprintf(ss, "%-10s ", mnemonic);
+    // Generate the correct mnemonic
+    std::string myMnemonic(mnemonic);
+
+    // Special cases
+    if (!myMnemonic.compare("srawi")) {
+        printSecondSrc = false;
+        printShift = true;
+    }
+
+    // Additional characters depending on isa bits being set
+    if (rcSet) myMnemonic = myMnemonic + ".";
+    ccprintf(ss, "%-10s ", myMnemonic);
 
     // Print the first destination only
     if (_numDestRegs > 0) {
@@ -598,10 +611,32 @@ IntShiftOp::generateDisassembly(
             ss << ", ";
         }
         printReg(ss, srcRegIdx(0));
+
+        // Print the second source register
+        if (printSecondSrc) {
+
+            // If the instruction updates the CR, the destination register
+            // Ra is read and thus, it becomes the second source register
+            // due to its higher precedence over Rb. In this case, it must
+            // be skipped.
+            if (rcSet) {
+                if (_numSrcRegs > 2) {
+                    ss << ", ";
+                    printReg(ss, srcRegIdx(2));
+                }
+            } else {
+                if (_numSrcRegs > 1) {
+                    ss << ", ";
+                    printReg(ss, srcRegIdx(1));
+                }
+            }
+        }
     }
 
-    // Print the shift
-    ss << ", " << sh;
+    // Print the shift value
+    if (printShift) {
+        ss << ", " << shift;
+    }
 
     return ss.str();
 }