From 5e2b05a71e81b28712b77419f68657462494e103 Mon Sep 17 00:00:00 2001
From: Bob Wilson <bob.wilson@apple.com>
Date: Wed, 10 Feb 2010 22:58:57 +0000
Subject: [PATCH] Delete dead PHI machine instructions.  These can be created
 due to type legalization even when the IR-level optimizer has removed dead
 phis, such as when the high half of an i64 value is unused on a 32-bit
 target. I had to adjust a few test cases that had dead phis. This is a
 partial fix for Radar 7627077.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95816 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/DeadMachineInstructionElim.cpp  | 2 +-
 test/CodeGen/ARM/remat.ll                   | 6 +++---
 test/CodeGen/X86/2007-10-05-3AddrConvert.ll | 4 +++-
 3 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/lib/CodeGen/DeadMachineInstructionElim.cpp b/lib/CodeGen/DeadMachineInstructionElim.cpp
index b0cb24d95f7..6e01e59349e 100644
--- a/lib/CodeGen/DeadMachineInstructionElim.cpp
+++ b/lib/CodeGen/DeadMachineInstructionElim.cpp
@@ -55,7 +55,7 @@ FunctionPass *llvm::createDeadMachineInstructionElimPass() {
 bool DeadMachineInstructionElim::isDead(const MachineInstr *MI) const {
   // Don't delete instructions with side effects.
   bool SawStore = false;
-  if (!MI->isSafeToMove(TII, SawStore, 0))
+  if (!MI->isSafeToMove(TII, SawStore, 0) && !MI->isPHI())
     return false;
 
   // Examine each operand.
diff --git a/test/CodeGen/ARM/remat.ll b/test/CodeGen/ARM/remat.ll
index 367f782e0ff..92c1cf18215 100644
--- a/test/CodeGen/ARM/remat.ll
+++ b/test/CodeGen/ARM/remat.ll
@@ -32,16 +32,16 @@ bb.i35:                                           ; preds = %bb142
   br label %phi1.exit
 
 phi1.exit:                                        ; preds = %bb.i35, %bb142
-  %.pn = phi double [ %6, %bb.i35 ], [ 0.000000e+00, %bb142 ] ; <double> [#uses=0]
+  %.pn = phi double [ %6, %bb.i35 ], [ 0.000000e+00, %bb142 ] ; <double> [#uses=1]
   %9 = phi double [ %8, %bb.i35 ], [ 0.000000e+00, %bb142 ] ; <double> [#uses=1]
-  %10 = fmul double undef, %9                     ; <double> [#uses=0]
+  %10 = fmul double %.pn, %9                      ; <double> [#uses=1]
   br i1 %14, label %phi0.exit, label %bb.i
 
 bb.i:                                             ; preds = %phi1.exit
   unreachable
 
 phi0.exit:                                        ; preds = %phi1.exit
-  %11 = fsub double %4, undef                     ; <double> [#uses=1]
+  %11 = fsub double %4, %10                       ; <double> [#uses=1]
   %12 = fadd double 0.000000e+00, %11             ; <double> [#uses=1]
   store double %12, double* undef, align 4
   br label %bb142
diff --git a/test/CodeGen/X86/2007-10-05-3AddrConvert.ll b/test/CodeGen/X86/2007-10-05-3AddrConvert.ll
index 67323e87eff..2c2706de5d3 100644
--- a/test/CodeGen/X86/2007-10-05-3AddrConvert.ll
+++ b/test/CodeGen/X86/2007-10-05-3AddrConvert.ll
@@ -36,7 +36,9 @@ bb.i6.i:		; preds = %bb.i6.i, %stepsystem.exit.i
 
 bb107.i.i:		; preds = %bb107.i.i, %bb.i6.i
 	%q_addr.0.i.i.in = phi %struct.bnode** [ null, %bb107.i.i ], [ %4, %bb.i6.i ]		; <%struct.bnode**> [#uses=1]
-	%q_addr.0.i.i = load %struct.bnode** %q_addr.0.i.i.in		; <%struct.bnode*> [#uses=0]
+	%q_addr.0.i.i = load %struct.bnode** %q_addr.0.i.i.in		; <%struct.bnode*> [#uses=1]
+	%q_addr.1 = getelementptr %struct.anon* %0, i32 0, i32 4, i32 1
+	store %struct.bnode* %q_addr.0.i.i, %struct.bnode** %q_addr.1, align 4
 	br label %bb107.i.i
 
 bb47.loopexit.i:		; preds = %bb32.i