[PATCH] D21395: Fix for Bug 28144 and print register preserved in comments in asm files

[Matthias Braun via llvm-commits]

MatzeB added inline comments.

================
Comment at: lib/CodeGen/AsmPrinter/AsmPrinter.cpp:659-673
@@ -656,1 +658,17 @@
+
+  if (MI.isCall()) {
+    const uint32_t *CalleeRegMask;
+    CommentOS << "Call Preserved Registers: ";
+
+    for (const MachineOperand &MO : MI.operands())
+      if (MO.isRegMask()) {
+        CalleeRegMask = MO.getRegMask();
+        break;
+      }
+
+    for (unsigned PReg = 1, PRegE = TRI->getNumRegs(); PReg < PRegE; ++PReg)
+      if (!MachineOperand::clobbersPhysReg(CalleeRegMask, PReg))
+        CommentOS << TRI->getName(PReg) << " ";
+    CommentOS << "\n";
+  }
 }
----------------
This part seems independent to me and could go into a separate commit.

================
Comment at: lib/CodeGen/RegUsageInfoCollector.cpp:113-126
@@ -112,1 +112,16 @@
 
+  for (MachineBasicBlock &MBB : MF) {
+    for (MachineInstr &MI : MBB) {
+      if (!MI.isCall())
+        continue;
+      for (MachineOperand &MO : MI.operands()) {
+        if (!MO.isRegMask())
+          continue;
+        const uint32_t *CalleeRegMask = MO.getRegMask();
+        for (unsigned i = 0; i < RegMaskSize; ++i)
+          RegMask[i] = RegMask[i] & CalleeRegMask[i];
+        break;
+      }
+    }
+  }
+
----------------
Note that the register allocator already computes this information. You can simply use something like `MachineRegisterInfo::getUsedPhysRegsMask()` to get it.


http://reviews.llvm.org/D21395