[llvm-commits] [llvm] r168360 - in /llvm/trunk: include/llvm/CodeGen/MachineInstrBundle.h lib/CodeGen/MachineBasicBlock.cpp lib/CodeGen/MachineInstrBundle.cpp test/CodeGen/ARM/domain-conv-vmovs.ll

[Tim Northover]

Author: tnorthover
Date: Tue Nov 20 03:56:11 2012
New Revision: 168360

URL: http://llvm.org/viewvc/llvm-project?rev=168360&view=rev
Log:
Fix physical register liveness calculations:

+ Take account of clobbers
+ Give outputs priority over inputs since they happen later.

Modified:
    llvm/trunk/include/llvm/CodeGen/MachineInstrBundle.h
    llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp
    llvm/trunk/lib/CodeGen/MachineInstrBundle.cpp
    llvm/trunk/test/CodeGen/ARM/domain-conv-vmovs.ll

Modified: llvm/trunk/include/llvm/CodeGen/MachineInstrBundle.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/MachineInstrBundle.h?rev=168360&r1=168359&r2=168360&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/MachineInstrBundle.h (original)
+++ llvm/trunk/include/llvm/CodeGen/MachineInstrBundle.h Tue Nov 20 03:56:11 2012
@@ -149,16 +149,13 @@
   /// PhysRegInfo - Information about a physical register used by a set of
   /// operands.
   struct PhysRegInfo {
-    /// Clobbers - Reg or an overlapping register is defined, or a regmask 
+    /// Clobbers - Reg or an overlapping register is defined, or a regmask
     /// clobbers Reg.
     bool Clobbers;
 
     /// Defines - Reg or a super-register is defined.
     bool Defines;
 
-    /// DefinesOverlap - Reg or an overlapping register is defined.
-    bool DefinesOverlap;
-
     /// Reads - Read or a super-register is read.
     bool Reads;
 

Modified: llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp?rev=168360&r1=168359&r2=168360&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp Tue Nov 20 03:56:11 2012
@@ -982,7 +982,6 @@
 MachineBasicBlock::computeRegisterLiveness(const TargetRegisterInfo *TRI,
                                            unsigned Reg, MachineInstr *MI,
                                            unsigned Neighborhood) {
-  
   unsigned N = Neighborhood;
   MachineBasicBlock *MBB = MI->getParent();
 
@@ -997,14 +996,18 @@
       MachineOperandIteratorBase::PhysRegInfo Analysis =
         MIOperands(I).analyzePhysReg(Reg, TRI);
 
-      if (Analysis.Kills)
+      if (Analysis.Defines)
+        // Outputs happen after inputs so they take precedence if both are
+        // present.
+        return Analysis.DefinesDead ? LQR_Dead : LQR_Live;
+
+      if (Analysis.Kills || Analysis.Clobbers)
         // Register killed, so isn't live.
         return LQR_Dead;
 
-      else if (Analysis.DefinesOverlap || Analysis.ReadsOverlap)
+      else if (Analysis.ReadsOverlap)
         // Defined or read without a previous kill - live.
-        return (Analysis.Defines || Analysis.Reads) ? 
-          LQR_Live : LQR_OverlappingLive;
+        return Analysis.Reads ? LQR_Live : LQR_OverlappingLive;
 
     } while (I != MBB->begin() && --N > 0);
   }
@@ -1036,7 +1039,7 @@
         return (Analysis.Reads) ?
           LQR_Live : LQR_OverlappingLive;
 
-      else if (Analysis.DefinesOverlap)
+      else if (Analysis.Clobbers || Analysis.Defines)
         // Defined (but not read) therefore cannot have been live.
         return LQR_Dead;
     }

Modified: llvm/trunk/lib/CodeGen/MachineInstrBundle.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineInstrBundle.cpp?rev=168360&r1=168359&r2=168360&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineInstrBundle.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineInstrBundle.cpp Tue Nov 20 03:56:11 2012
@@ -281,7 +281,7 @@
 MachineOperandIteratorBase::analyzePhysReg(unsigned Reg,
                                            const TargetRegisterInfo *TRI) {
   bool AllDefsDead = true;
-  PhysRegInfo PRI = {false, false, false, false, false, false, false};
+  PhysRegInfo PRI = {false, false, false, false, false, false};
 
   assert(TargetRegisterInfo::isPhysicalRegister(Reg) &&
          "analyzePhysReg not given a physical register!");
@@ -305,7 +305,9 @@
       // Reg or a super-reg is read, and perhaps killed also.
       PRI.Reads = true;
       PRI.Kills = MO.isKill();
-    } if (IsRegOrOverlapping && MO.readsReg()) {
+    }
+
+    if (IsRegOrOverlapping && MO.readsReg()) {
       PRI.ReadsOverlap = true;// Reg or an overlapping register is read.
     }
 

Modified: llvm/trunk/test/CodeGen/ARM/domain-conv-vmovs.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/domain-conv-vmovs.ll?rev=168360&r1=168359&r2=168360&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/domain-conv-vmovs.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/domain-conv-vmovs.ll Tue Nov 20 03:56:11 2012
@@ -98,3 +98,23 @@
 
   ret i32 %resi
 }
+
+
+; The point of this test is:
+;   + Make sure s1 is live before the BL
+;   + Make sure s1 is clobbered by the BL
+;   + Convince LLVM to emit a VMOV to S0
+;   + Convince LLVM to domain-convert this.
+
+; When all of those are satisfied, LLVM should *not* mark s1 as an implicit-use
+; because it's dead.
+
+declare float @clobbers_s1(float, float)
+
+define <2 x float> @test_clobbers_recognised(<2 x float> %invec, float %val) {
+  %elt = call float @clobbers_s1(float %val, float %val)
+
+  %vec = insertelement <2 x float> %invec, float %elt, i32 0
+  %res = fadd <2 x float> %vec, %vec
+  ret <2 x float> %res
+}