Be more aggressive about following hints.
RAGreedy::tryAssign will now evict interference from the preferred
register even when another register is free.
To support this, add the EvictionCost struct that counts how many hints
are broken by an eviction. We don't want to break one hint just to
satisfy another.
Rename canEvict to shouldEvict, and add the first bit of eviction policy
that doesn't depend on spill weights: Always make room in the preferred
register as long as the evictees can be split and aren't already
assigned to their preferred register.
Also make the CSR avoidance more accurate. When looking for a cheaper
register it is OK to use a new volatile register. Only CSR aliases that
have never been used before should be avoided.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134735 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/VirtRegMap.h b/lib/CodeGen/VirtRegMap.h
index ba50f4e..03abff3 100644
--- a/lib/CodeGen/VirtRegMap.h
+++ b/lib/CodeGen/VirtRegMap.h
@@ -208,6 +208,11 @@
/// @brief returns the register allocation preference.
unsigned getRegAllocPref(unsigned virtReg);
+ /// @brief returns true if VirtReg is assigned to its preferred physreg.
+ bool hasPreferredPhys(unsigned VirtReg) {
+ return getPhys(VirtReg) == getRegAllocPref(VirtReg);
+ }
+
/// @brief records virtReg is a split live interval from SReg.
void setIsSplitFromReg(unsigned virtReg, unsigned SReg) {
Virt2SplitMap[virtReg] = SReg;