[llvm-commits] [llvm] r145056 - in /llvm/trunk: lib/CodeGen/RegAllocFast.cpp test/CodeGen/X86/pr11415.ll

[Rafael Espindola]

Author: rafael
Date: Tue Nov 22 00:27:18 2011
New Revision: 145056

URL: http://llvm.org/viewvc/llvm-project?rev=145056&view=rev
Log:
If a register is both an early clobber and part of a tied use, handle the use
before the clobber so that we copy the value if needed.

Fixes pr11415.

Added:
    llvm/trunk/test/CodeGen/X86/pr11415.ll
Modified:
    llvm/trunk/lib/CodeGen/RegAllocFast.cpp

Modified: llvm/trunk/lib/CodeGen/RegAllocFast.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegAllocFast.cpp?rev=145056&r1=145055&r2=145056&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/RegAllocFast.cpp (original)
+++ llvm/trunk/lib/CodeGen/RegAllocFast.cpp Tue Nov 22 00:27:18 2011
@@ -682,7 +682,7 @@
   }
 
   SmallVector<unsigned, 8> PartialDefs;
-  DEBUG(dbgs() << "Allocating tied uses and early clobbers.\n");
+  DEBUG(dbgs() << "Allocating tied uses.\n");
   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
     MachineOperand &MO = MI->getOperand(i);
     if (!MO.isReg()) continue;
@@ -704,15 +704,24 @@
       // That would confuse the later phys-def processing pass.
       LiveRegMap::iterator LRI = reloadVirtReg(MI, i, Reg, 0);
       PartialDefs.push_back(LRI->second.PhysReg);
-    } else if (MO.isEarlyClobber()) {
-      // Note: defineVirtReg may invalidate MO.
-      LiveRegMap::iterator LRI = defineVirtReg(MI, i, Reg, 0);
-      unsigned PhysReg = LRI->second.PhysReg;
-      if (setPhysReg(MI, i, PhysReg))
-        VirtDead.push_back(Reg);
     }
   }
 
+  DEBUG(dbgs() << "Allocating early clobbers.\n");
+  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+    MachineOperand &MO = MI->getOperand(i);
+    if (!MO.isReg()) continue;
+    unsigned Reg = MO.getReg();
+    if (!TargetRegisterInfo::isVirtualRegister(Reg)) continue;
+    if (!MO.isEarlyClobber())
+      continue;
+    // Note: defineVirtReg may invalidate MO.
+    LiveRegMap::iterator LRI = defineVirtReg(MI, i, Reg, 0);
+    unsigned PhysReg = LRI->second.PhysReg;
+    if (setPhysReg(MI, i, PhysReg))
+      VirtDead.push_back(Reg);
+  }
+
   // Restore UsedInInstr to a state usable for allocating normal virtual uses.
   UsedInInstr.reset();
   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {

Added: llvm/trunk/test/CodeGen/X86/pr11415.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/pr11415.ll?rev=145056&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/pr11415.ll (added)
+++ llvm/trunk/test/CodeGen/X86/pr11415.ll Tue Nov 22 00:27:18 2011
@@ -0,0 +1,23 @@
+; RUN: llc %s -o - -regalloc=fast | FileCheck %s
+
+; We used to consider the early clobber in the second asm statement as
+; defining %0 before it was read. This caused us to omit the
+; movq	-8(%rsp), %rdx
+
+; CHECK: 	#APP
+; CHECK-NEXT:	#NO_APP
+; CHECK-NEXT:	movq	%rcx, %rax
+; CHECK-NEXT:	movq	%rax, -8(%rsp)
+; CHECK-NEXT:	movq	-8(%rsp), %rdx
+; CHECK-NEXT:	#APP
+; CHECK-NEXT:	#NO_APP
+; CHECK-NEXT:	movq	%rdx, %rax
+; CHECK-NEXT:	movq	%rdx, -8(%rsp)
+; CHECK-NEXT:	ret
+
+define i64 @foo() {
+entry:
+  %0 = tail call i64 asm "", "={cx}"() nounwind
+  %1 = tail call i64 asm "", "=&r,0,r,~{rax}"(i64 %0, i64 %0) nounwind
+  ret i64 %1
+}