[PATCH] D57314: [PowerPC] more opportunity for converting reg+reg to reg+imm

[ChenZheng via Phabricator via llvm-commits]

shchenz created this revision.
shchenz added reviewers: qshanz, nemanjai, jsji, hfinkel.
Herald added a subscriber: hiraditya.

PowerPC should convert following reg+reg to reg+imm.

  body: |
    bb.0.entry:
      liveins: $x3, $f1, $x5  
      $x3 = ADDI8 $x5, 100  
      STFSX killed $f1, $zero8, $x3  
      STD killed $x3, killed $x5, 100  
      BLR8 implicit $lr8, implicit $rm 

Fix the bug to make it work.


https://reviews.llvm.org/D57314

Files:
  llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
  llvm/test/CodeGen/PowerPC/convert-rr-to-ri-instr-add.mir


Index: llvm/test/CodeGen/PowerPC/convert-rr-to-ri-instr-add.mir
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/PowerPC/convert-rr-to-ri-instr-add.mir
@@ -0,0 +1,16 @@
+# RUN: llc -mtriple=powerpc64le--linux-gnu -stop-after ppc-pre-emit-peephole %s -o - -verify-machineinstrs | FileCheck %s
+
+---
+name: testFwdOperandKilledAfter
+# CHECK: name: testFwdOperandKilledAfter
+tracksRegLiveness: true 
+body: |
+  bb.0.entry:
+    liveins: $x3, $f1, $x5  
+    $x3 = ADDI8 $x5, 100  
+    STFSX killed $f1, $zero8, $x3  
+    ; CHECK: STFS killed $f1, 100, $x5  
+    STD killed $x3, killed $x5, 100  
+    ; CHECK: STD killed $x3, killed $x5, 100  
+    BLR8 implicit $lr8, implicit $rm 
+...
Index: llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
===================================================================
--- llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
+++ llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
@@ -3207,7 +3207,7 @@
 
   // If DefMI also uses the register to be forwarded, we can only forward it
   // if DefMI is being erased.
-  if (DefMI.readsRegister(Reg, &getRegisterInfo()))
+  if (DefMI.modifiesRegister(Reg, &getRegisterInfo()))
     return KillDefMI;
 
   return true;


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