commit 7f370b615515af6422eb0d5d08f1c4c5db95fbbc
author Hal Finkel <hfinkel@anl.gov> Thu Dec 15 17:54:01 2011 +0000
committer Hal Finkel <hfinkel@anl.gov> Thu Dec 15 17:54:01 2011 +0000
tree e0041b5aef835bf8d9e515d21595bc8ea1679dbd
parent 7e56831a6804812b2295c5446a05f4ec457b6b3e

Ensure that the nop that should follow a bl call in PPC64 ELF actually does

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146664 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/PowerPC/PPCHazardRecognizers.cpp

diff --git a/lib/Target/PowerPC/PPCHazardRecognizers.cpp b/lib/Target/PowerPC/PPCHazardRecognizers.cpp
index c90e295..ae317af 100644
--- a/lib/Target/PowerPC/PPCHazardRecognizers.cpp
+++ b/lib/Target/PowerPC/PPCHazardRecognizers.cpp
@@ -61,6 +61,7 @@
 
 PPCHazardRecognizer970::PPCHazardRecognizer970(const TargetInstrInfo &tii)
   : TII(tii) {
+  LastWasBL8_ELF = false;
   EndDispatchGroup();
 }
 
@@ -132,6 +133,14 @@
 
   unsigned Opcode = MI->getOpcode();
 
+  // If the last instruction was a BL8_ELF, then the NOP must follow it
+  // directly (this is strong requirement from the linker due to the ELF ABI).
+  // We return only Hazard (and not NoopHazard) because if the NOP is necessary
+  // then it will already be in the instruction stream (it is not always
+  // necessary; tail calls, for example, do not need it).
+  if (LastWasBL8_ELF && Opcode != PPC::NOP)
+    return Hazard;
+
   bool isFirst, isSingle, isCracked, isLoad, isStore;
   PPCII::PPC970_Unit InstrType =
     GetInstrType(Opcode, isFirst, isSingle, isCracked,
@@ -190,6 +199,7 @@
     return;
 
   unsigned Opcode = MI->getOpcode();
+  LastWasBL8_ELF = (Opcode == PPC::BL8_ELF);
 
   bool isFirst, isSingle, isCracked, isLoad, isStore;
   PPCII::PPC970_Unit InstrType =
@@ -230,6 +240,7 @@
 }
 
 void PPCHazardRecognizer970::Reset() {
+  LastWasBL8_ELF = false;
   EndDispatchGroup();
 }