[llvm-commits] [llvm] r82342 - in /llvm/trunk: lib/CodeGen/LiveIntervalAnalysis.cpp test/CodeGen/X86/2009-09-19-earlyclobber.ll

[Dale Johannesen]

Author: johannes
Date: Sat Sep 19 19:36:41 2009
New Revision: 82342

URL: http://llvm.org/viewvc/llvm-project?rev=82342&view=rev
Log:
When computing live intervals for earlyclobber operands,
we pushed the beginning of the interval back 1, so the
interval would overlap with inputs that die.  We were
also pushing the end of the interval back 1, though,
which means the earlyclobber didn't overlap with other
output operands.  Don't do this.  PR 4964.


Added:
    llvm/trunk/test/CodeGen/X86/2009-09-19-earlyclobber.ll
Modified:
    llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp

Modified: llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp?rev=82342&r1=82341&r2=82342&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp (original)
+++ llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp Sat Sep 19 19:36:41 2009
@@ -665,7 +665,8 @@
   if (interval.empty()) {
     // Get the Idx of the defining instructions.
     MachineInstrIndex defIndex = getDefIndex(MIIdx);
-    // Earlyclobbers move back one.
+    // Earlyclobbers move back one, so that they overlap the live range
+    // of inputs.
     if (MO.isEarlyClobber())
       defIndex = getUseIndex(MIIdx);
     VNInfo *ValNo;
@@ -690,6 +691,11 @@
       MachineInstrIndex killIdx;
       if (vi.Kills[0] != mi)
         killIdx = getNextSlot(getUseIndex(getInstructionIndex(vi.Kills[0])));
+      else if (MO.isEarlyClobber())
+        // Earlyclobbers that die in this instruction move up one extra, to
+        // compensate for having the starting point moved back one.  This
+        // gets them to overlap the live range of other outputs.
+        killIdx = getNextSlot(getNextSlot(defIndex));
       else
         killIdx = getNextSlot(defIndex);
 
@@ -791,7 +797,9 @@
       // range covering the def slot.
       if (MO.isDead())
         interval.addRange(
-          LiveRange(RedefIndex, getNextSlot(RedefIndex), OldValNo));
+          LiveRange(RedefIndex, MO.isEarlyClobber() ?
+                                getNextSlot(getNextSlot(RedefIndex)) :
+                                getNextSlot(RedefIndex), OldValNo));
 
       DEBUG({
           errs() << " RESULT: ";
@@ -892,9 +900,14 @@
   // If it is not used after definition, it is considered dead at
   // the instruction defining it. Hence its interval is:
   // [defSlot(def), defSlot(def)+1)
+  // For earlyclobbers, the defSlot was pushed back one; the extra
+  // advance below compensates.
   if (MO.isDead()) {
     DEBUG(errs() << " dead");
-    end = getNextSlot(start);
+    if (MO.isEarlyClobber())
+      end = getNextSlot(getNextSlot(start));
+    else
+      end = getNextSlot(start);
     goto exit;
   }
 

Added: llvm/trunk/test/CodeGen/X86/2009-09-19-earlyclobber.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/2009-09-19-earlyclobber.ll?rev=82342&view=auto

==============================================================================
--- llvm/trunk/test/CodeGen/X86/2009-09-19-earlyclobber.ll (added)
+++ llvm/trunk/test/CodeGen/X86/2009-09-19-earlyclobber.ll Sat Sep 19 19:36:41 2009
@@ -0,0 +1,15 @@
+; RUN: llc < %s | FileCheck %s
+; ModuleID = '4964.c'
+; PR 4964
+; Registers other than RAX, RCX are OK, but they must be different.
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
+target triple = "x86_64-apple-darwin10.0"
+	type { i64, i64 }		; type %0
+
+define i64 @flsst(i64 %find) nounwind ssp {
+entry:
+; CHECK: FOO %rax %rcx
+	%asmtmp = tail call %0 asm sideeffect "FOO $0 $1 $2", "=r,=&r,rm,~{dirflag},~{fpsr},~{flags},~{cc}"(i64 %find) nounwind		; <%0> [#uses=1]
+	%asmresult = extractvalue %0 %asmtmp, 0		; <i64> [#uses=1]
+	ret i64 %asmresult
+}