[llvm-commits] [llvm] r99096 - in /llvm/trunk: lib/Target/ARM/ARMLoadStoreOptimizer.cpp test/CodeGen/ARM/2010-03-18-ldm-rtrn.ll

[Bob Wilson]

Author: bwilson
Date: Sat Mar 20 17:20:40 2010
New Revision: 99096

URL: http://llvm.org/viewvc/llvm-project?rev=99096&view=rev
Log:
pr6652: Use LDM to restore PC to the return address on ARMv4.
Patch by John Tytgat!

Added:
    llvm/trunk/test/CodeGen/ARM/2010-03-18-ldm-rtrn.ll
Modified:
    llvm/trunk/lib/Target/ARM/ARMLoadStoreOptimizer.cpp

Modified: llvm/trunk/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMLoadStoreOptimizer.cpp?rev=99096&r1=99095&r2=99096&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMLoadStoreOptimizer.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMLoadStoreOptimizer.cpp Sat Mar 20 17:20:40 2010
@@ -1155,19 +1155,24 @@
   };
 }
 
-/// MergeReturnIntoLDM - If this is a exit BB, try merging the return op
-/// (bx lr) into the preceeding stack restore so it directly restore the value
-/// of LR into pc.
-///   ldmfd sp!, {r7, lr}
+/// MergeReturnIntoLDM - If this is a exit BB, try merging the return ops
+/// ("bx lr" and "mov pc, lr") into the preceeding stack restore so it
+/// directly restore the value of LR into pc.
+///   ldmfd sp!, {..., lr}
 ///   bx lr
+/// or
+///   ldmfd sp!, {..., lr}
+///   mov pc, lr
 /// =>
-///   ldmfd sp!, {r7, pc}
+///   ldmfd sp!, {..., pc}
 bool ARMLoadStoreOpt::MergeReturnIntoLDM(MachineBasicBlock &MBB) {
   if (MBB.empty()) return false;
 
   MachineBasicBlock::iterator MBBI = prior(MBB.end());
   if (MBBI != MBB.begin() &&
-      (MBBI->getOpcode() == ARM::BX_RET || MBBI->getOpcode() == ARM::tBX_RET)) {
+      (MBBI->getOpcode() == ARM::BX_RET ||
+       MBBI->getOpcode() == ARM::tBX_RET ||
+       MBBI->getOpcode() == ARM::MOVPCLR)) {
     MachineInstr *PrevMI = prior(MBBI);
     if (PrevMI->getOpcode() == ARM::LDM_UPD ||
         PrevMI->getOpcode() == ARM::t2LDM_UPD) {

Added: llvm/trunk/test/CodeGen/ARM/2010-03-18-ldm-rtrn.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/2010-03-18-ldm-rtrn.ll?rev=99096&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/2010-03-18-ldm-rtrn.ll (added)
+++ llvm/trunk/test/CodeGen/ARM/2010-03-18-ldm-rtrn.ll Sat Mar 20 17:20:40 2010
@@ -0,0 +1,13 @@
+; RUN: llc < %s -mtriple=armv4-unknown-eabi | FileCheck %s
+; RUN: llc < %s -mtriple=armv5-unknown-eabi | FileCheck %s
+; RUN: llc < %s -mtriple=armv6-unknown-eabi | FileCheck %s
+
+define i32 @bar(i32 %a) nounwind {
+entry:
+  %0 = tail call i32 @foo(i32 %a) nounwind ; <i32> [#uses=1]
+  %1 = add nsw i32 %0, 3                          ; <i32> [#uses=1]
+; CHECK: ldmia	sp!, {r11, pc}
+  ret i32 %1
+}
+
+declare i32 @foo(i32)