Make linear scan's trivial coalescer slightly more aggressive.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62547 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 14 insertions, 6 deletions

diff --git a/lib/CodeGen/RegAllocLinearScan.cpp b/lib/CodeGen/RegAllocLinearScan.cpp
index 1e7d0a8..96f8ab4 100644
--- a/lib/CodeGen/RegAllocLinearScan.cpp
+++ b/lib/CodeGen/RegAllocLinearScan.cpp
@@ -249,7 +249,7 @@ unsigned RALinScan::attemptTrivialCoalescing(LiveInterval &cur, unsigned Reg) {
   if ((cur.preference && cur.preference == Reg) || !cur.containsOneValue())
     return Reg;
 
-  VNInfo *vni = cur.getValNumInfo(0);
+  VNInfo *vni = cur.begin()->valno;
   if (!vni->def || vni->def == ~1U || vni->def == ~0U)
     return Reg;
   MachineInstr *CopyMI = li_->getInstructionFromIndex(vni->def);
@@ -686,13 +686,13 @@ void RALinScan::assignRegOrStackSlotAtInterval(LiveInterval* cur)
   unsigned StartPosition = cur->beginNumber();
   const TargetRegisterClass *RCLeader = RelatedRegClasses.getLeaderValue(RC);
 
-  // If this live interval is defined by a move instruction and its source is
-  // assigned a physical register that is compatible with the target register
-  // class, then we should try to assign it the same register.
+  // If start of this live interval is defined by a move instruction and its
+  // source is assigned a physical register that is compatible with the target
+  // register class, then we should try to assign it the same register.
   // This can happen when the move is from a larger register class to a smaller
   // one, e.g. X86::mov32to32_. These move instructions are not coalescable.
-  if (!cur->preference && cur->containsOneValue()) {
-    VNInfo *vni = cur->getValNumInfo(0);
+  if (!cur->preference && cur->hasAtLeastOneValue()) {
+    VNInfo *vni = cur->begin()->valno;
     if (vni->def && vni->def != ~1U && vni->def != ~0U) {
       MachineInstr *CopyMI = li_->getInstructionFromIndex(vni->def);
       unsigned SrcReg, DstReg;
diff --git a/test/CodeGen/X86/uint_to_fp-2.ll b/test/CodeGen/X86/uint_to_fp-2.ll
new file mode 100644
index 0000000..d630437
--- /dev/null
+++ b/test/CodeGen/X86/uint_to_fp-2.ll
@@ -0,0 +1,8 @@
+; RUN: llvm-as < %s | llc -march=x86 -mattr=+sse2 | grep movsd | count 1
+; rdar://6504833
+
+define float @f(i32 %x) nounwind readnone {
+entry:
+	%0 = uitofp i32 %x to float
+	ret float %0
+}