From c801057a20161fef2a12959b2503729940b9d36c Mon Sep 17 00:00:00 2001
From: Carol Eidt <carol.eidt@microsoft.com>
Date: Wed, 21 Mar 2018 15:13:17 -0700
Subject: [PATCH] Remove REG_OPT_RSVD from LSRA's candidate masks if it's
 reserved.

---
 src/jit/lsra.cpp | 40 ++++++++++++++++++++++++----------------
 src/jit/lsra.h   |  2 +-
 2 files changed, 25 insertions(+), 17 deletions(-)

diff --git a/src/jit/lsra.cpp b/src/jit/lsra.cpp
index 5399bb5..090cc05 100644
--- a/src/jit/lsra.cpp
+++ b/src/jit/lsra.cpp
@@ -824,19 +824,24 @@ LinearScan::RegMaskIndex LinearScan::GetIndexForRegMask(regMaskTP mask)
     return result;
 }
 
-// We've decided that we can't use a register during register allocation (probably FPBASE),
+// We've decided that we can't use one or more registers during register allocation (probably FPBASE),
 // but we've already added it to the register masks. Go through the masks and remove it.
-void LinearScan::RemoveRegisterFromMasks(regNumber reg)
+void LinearScan::RemoveRegistersFromMasks(regMaskTP removeMask)
 {
-    JITDUMP("Removing register %s from LSRA register masks\n", getRegName(reg));
+    if (VERBOSE)
+    {
+        JITDUMP("Removing registers from LSRA register masks: ");
+        dumpRegMask(removeMask);
+        JITDUMP("\n");
+    }
 
-    regMaskTP mask = ~genRegMask(reg);
+    regMaskTP mask = ~removeMask;
     for (int i = 0; i < nextFreeMask; i++)
     {
         regMaskTable[i] &= mask;
     }
 
-    JITDUMP("After removing register:\n");
+    JITDUMP("After removing registers:\n");
     DBEXEC(VERBOSE, dspRegisterMaskTable());
 }
 
@@ -2493,19 +2498,10 @@ void LinearScan::setFrameType()
     // used during lowering. Luckily, the TreeNodeInfo only stores an index to
     // the masks stored in the LinearScan class, so we only need to walk the
     // unique masks and remove FPBASE.
+    regMaskTP removeMask = RBM_NONE;
     if (frameType == FT_EBP_FRAME)
     {
-        if ((availableIntRegs & RBM_FPBASE) != 0)
-        {
-            RemoveRegisterFromMasks(REG_FPBASE);
-
-            // We know that we're already in "read mode" for availableIntRegs. However,
-            // we need to remove the FPBASE register, so subsequent users (like callers
-            // to allRegs()) get the right thing. The RemoveRegisterFromMasks() code
-            // fixes up everything that already took a dependency on the value that was
-            // previously read, so this completes the picture.
-            availableIntRegs.OverrideAssign(availableIntRegs & ~RBM_FPBASE);
-        }
+        removeMask |= RBM_FPBASE;
     }
 
     compiler->rpFrameType = frameType;
@@ -2518,8 +2514,20 @@ void LinearScan::setFrameType()
         compiler->codeGen->regSet.rsMaskResvd |= RBM_OPT_RSVD;
         assert(REG_OPT_RSVD != REG_FP);
         JITDUMP("  Reserved REG_OPT_RSVD (%s) due to large frame\n", getRegName(REG_OPT_RSVD));
+        removeMask |= RBM_OPT_RSVD;
     }
 #endif // _TARGET_ARMARCH_
+
+    if ((removeMask != RBM_NONE) && ((availableIntRegs & removeMask) != 0))
+    {
+        RemoveRegistersFromMasks(removeMask);
+        // We know that we're already in "read mode" for availableIntRegs. However,
+        // we need to remove these registers, so subsequent users (like callers
+        // to allRegs()) get the right thing. The RemoveRegistersFromMasks() code
+        // fixes up everything that already took a dependency on the value that was
+        // previously read, so this completes the picture.
+        availableIntRegs.OverrideAssign(availableIntRegs & ~removeMask);
+    }
 }
 
 //------------------------------------------------------------------------
diff --git a/src/jit/lsra.h b/src/jit/lsra.h
index fe1d713..62ba386 100644
--- a/src/jit/lsra.h
+++ b/src/jit/lsra.h
@@ -695,7 +695,7 @@ public:
 
     RegMaskIndex GetIndexForRegMask(regMaskTP mask);
     regMaskTP GetRegMaskForIndex(RegMaskIndex index);
-    void RemoveRegisterFromMasks(regNumber reg);
+    void RemoveRegistersFromMasks(regMaskTP removeMask);
 
     static bool isSingleRegister(regMaskTP regMask)
     {
-- 
2.7.4