[PATCH] D21960: [Sparc] Leon errata fixes passes.

[Chris Dewhurst via llvm-commits]

lero_chris added a comment.

Addressing review comments.


================
Comment at: lib/Target/Sparc/LeonFeatures.td:66-69
@@ -65,6 +65,6 @@
 def PreventRoundChange
     : SubtargetFeature<"prvntroundchange", "PreventRoundChange", "true",
                        "LEON3 erratum fix: Prevent any rounding mode change "
                        "request: use only the round-to-nearest rounding mode">;
 
 def FixAllFDIVSQRT
----------------
Warning now issued when this pass makes any changes.

================
Comment at: lib/Target/Sparc/LeonFeatures.td:82-86
@@ -87,5 +81,7 @@
 def InsertNOPsLoadStore
     : SubtargetFeature<"insertnopsloadstore", "InsertNOPsLoadStore", "true",
                        "LEON3 erratum fix: Insert NOPs between "
                        "single-precision loads and the store, so the number of "
                        "instructions between is 4">;
+
+def FillDataCache : SubtargetFeature<"filldatacache", "FillDataCache", "true",
----------------
Removed this pass if it does nothing.

================
Comment at: lib/Target/Sparc/LeonPasses.cpp:231-232
@@ -261,26 +230,4 @@
         Reg2Index = MI.getOperand(1).getReg();
         Reg3Index = MI.getOperand(2).getReg();
-      } else if (MI.isInlineAsm()) {
-        StringRef AsmString =
-            MI.getOperand(InlineAsm::MIOp_AsmString).getSymbolName();
-        if (AsmString.startswith_lower("fmuls")) {
-          // this is an inline FMULS instruction
-          unsigned StartOp = InlineAsm::MIOp_FirstOperand;
-
-          // extracts the registers from the inline assembly instruction
-          for (unsigned i = StartOp, e = MI.getNumOperands(); i != e; ++i) {
-            const MachineOperand &MO = MI.getOperand(i);
-            if (MO.isReg()) {
-              if (Reg1Index == UNASSIGNED_INDEX)
-                Reg1Index = MO.getReg();
-              else if (Reg2Index == UNASSIGNED_INDEX)
-                Reg2Index = MO.getReg();
-              else if (Reg3Index == UNASSIGNED_INDEX)
-                Reg3Index = MO.getReg();
-            }
-            if (Reg3Index != UNASSIGNED_INDEX)
-              break;
-          }
-        }
       }
 
----------------
All inline assembly code removed.

================
Comment at: lib/Target/Sparc/LeonPasses.cpp:757-762
@@ +756,8 @@
+//
+// mov 0, %l0
+// mov 4096, %l1
+// loop1:
+// inc %l0
+// cmp %l0, %l1
+// ble loop1
+
----------------
A cache stores recently-accessed data. To fill the cache, we need to access data big enough to fill the L1 cache of the LEON 2 FT CPU. To solve this problem, we use NOP instructions to fill a block of memory with NOP instructions. The LEON 2’s L1 data cache is 16 KB [6] and the size of the NOP instruction is 4 Bytes. Therefore, we need 4096 NOPs to entirely fill the cache. Note this will happen only once at the first call of the runOnMachineFunction() method.

================
Comment at: lib/Target/Sparc/LeonPasses.cpp:851-859
@@ +850,11 @@
+//****************************************************************************************************************
+// This erratum fix should handle user traps of FPU exceptions and restore the
+// execution address by skipping the trapped FPU instruction.
+// The algorithm:
+// find rett - return from trap
+// insert code before rett to:
+// 1. load the FSR register
+// 2. check if there is an FPU exception
+// 3. branch to old rett if there is no exception
+// 4. rett to a restored exec address
+char RestoreExecAddress::ID = 0;
----------------
Do you suggest that this pass should not be part of the compiler then? I can remove it if it fixes nothing.

================
Comment at: lib/Target/Sparc/LeonPasses.h:108-110
@@ +107,5 @@
+
+  const char *getPassName() const override {
+    return "FillDataCache: Leon erratum fix: fill data cache with values at application startup";
+  }
+};
----------------
Removed these internal project reference codes.


================
Comment at: lib/Target/Sparc/LeonPasses.h:188
@@ -161,3 +187,3 @@
   const char *getPassName() const override {
-    return "InsertNOPLoad: insert a NOP instruction after "
+    return "InsertNOPLoad: Leon erratum fix: Insert a NOP instruction after "
            "every single-cycle load instruction when the next instruction is "
----------------
Removed these internal project reference codes.

================
Comment at: lib/Target/Sparc/Sparc.td:145
@@ -143,3 +144,3 @@
                 [ FeatureLeon, LeonCASA ]> {}
 
 //===----------------------------------------------------------------------===//
----------------
Removed from feature set.


Repository:
  rL LLVM

https://reviews.llvm.org/D21960