From: Dan Gohman <gohman@apple.com>
Date: Fri, 25 Sep 2009 23:58:45 +0000 (+0000)
Subject: Unbreak MachineLICM for instructions that reference RIP on x86-64 too.
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=a8fb336c2e7b8beb00d96a0992c41d38f0310a8f;p=oota-llvm.git

Unbreak MachineLICM for instructions that reference RIP on x86-64 too.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82825 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/MachineLICM.cpp b/lib/CodeGen/MachineLICM.cpp
index bb0d832172d..8123d99680b 100644
--- a/lib/CodeGen/MachineLICM.cpp
+++ b/lib/CodeGen/MachineLICM.cpp
@@ -43,6 +43,7 @@ namespace {
   class VISIBILITY_HIDDEN MachineLICM : public MachineFunctionPass {
     const TargetMachine   *TM;
     const TargetInstrInfo *TII;
+    const TargetRegisterInfo *TRI;
 
     // Various analyses that we use...
     MachineLoopInfo      *LI;      // Current MachineLoopInfo
@@ -135,6 +136,7 @@ bool MachineLICM::runOnMachineFunction(MachineFunction &MF) {
   Changed = false;
   TM = &MF.getTarget();
   TII = TM->getInstrInfo();
+  TRI = TM->getRegisterInfo();
   RegInfo = &MF.getRegInfo();
 
   // Get our Loop information...
@@ -254,8 +256,25 @@ bool MachineLICM::IsLoopInvariantInst(MachineInstr &I) {
     if (Reg == 0) continue;
 
     // Don't hoist an instruction that uses or defines a physical register.
-    if (TargetRegisterInfo::isPhysicalRegister(Reg))
-      return false;
+    if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
+      // If this is a physical register use, we can't move it.  If it is a def,
+      // we can move it, but only if the def is dead.
+      if (MO.isUse()) {
+        // If the physreg has no defs anywhere, it's just an ambient register
+        // and we can freely move its uses.
+        if (!RegInfo->def_empty(Reg))
+          return false;
+        // Check for a def among the register's aliases too.
+        for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias)
+          if (!RegInfo->def_empty(*Alias))
+            return false;
+        // Otherwise it's safe to move.
+        continue;
+      } else if (!MO.isDead()) {
+        // A def that isn't dead. We can't move it.
+        return false;
+      }
+    }
 
     if (!MO.isUse())
       continue;
diff --git a/test/CodeGen/X86/sink-hoist.ll b/test/CodeGen/X86/sink-hoist.ll
new file mode 100644
index 00000000000..24f2f94d7b2
--- /dev/null
+++ b/test/CodeGen/X86/sink-hoist.ll
@@ -0,0 +1,42 @@
+; RUN: llc < %s -march=x86-64 -asm-verbose=false | FileCheck %s
+
+; Currently, floating-point selects are lowered to CFG triangles.
+; This means that one side of the select is always unconditionally
+; evaluated, however with MachineSink we can sink the other side so
+; that it's conditionally evaluated.
+
+; CHECK: foo:
+; CHECK-NEXT: divsd
+; CHECK-NEXT: testb $1, %dil
+; CHECK-NEXT: jne
+
+define double @foo(double %x, double %y, i1 %c) nounwind {
+  %a = fdiv double %x, 3.2
+  %b = fdiv double %y, 3.3
+  %z = select i1 %c, double %a, double %b
+  ret double %z
+}
+
+; Hoist floating-point constant-pool loads out of loops.
+
+; CHECK: bar:
+; CHECK: movsd
+; CHECK: align
+define void @bar(double* nocapture %p, i64 %n) nounwind {
+entry:
+  %0 = icmp sgt i64 %n, 0
+  br i1 %0, label %bb, label %return
+
+bb:
+  %i.03 = phi i64 [ 0, %entry ], [ %3, %bb ]
+  %scevgep = getelementptr double* %p, i64 %i.03
+  %1 = load double* %scevgep, align 8
+  %2 = fdiv double 3.200000e+00, %1
+  store double %2, double* %scevgep, align 8
+  %3 = add nsw i64 %i.03, 1
+  %exitcond = icmp eq i64 %3, %n
+  br i1 %exitcond, label %return, label %bb
+
+return:
+  ret void
+}
diff --git a/test/CodeGen/X86/sink.ll b/test/CodeGen/X86/sink.ll
deleted file mode 100644
index 1d128b9006f..00000000000
--- a/test/CodeGen/X86/sink.ll
+++ /dev/null
@@ -1,18 +0,0 @@
-; RUN: llc < %s -march=x86-64 -asm-verbose=false | FileCheck %s
-
-; Currently, floating-point selects are lowered to CFG triangles.
-; This means that one side of the select is always unconditionally
-; evaluated, however with MachineSink we can sink the other side so
-; that it's conditionally evaluated.
-
-; CHECK: foo:
-; CHECK-NEXT: divsd
-; CHECK-NEXT: testb $1, %dil
-; CHECK-NEXT: jne
-
-define double @foo(double %x, double %y, i1 %c) nounwind {
-  %a = fdiv double %x, 3.2
-  %b = fdiv double %y, 3.3
-  %z = select i1 %c, double %a, double %b
-  ret double %z
-}