From ccbe603869681aa71b4140e3bf4b4459caf60622 Mon Sep 17 00:00:00 2001
From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Fri, 14 Oct 2011 01:00:49 +0000
Subject: [PATCH] Ban rematerializable instructions with side effects.

TableGen infers unmodeled side effects on instructions without a
pattern.  Fix some instruction definitions where that was overlooked.

Also raise an error if a rematerializable instruction has unmodeled side
effects. That doen't make any sense.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141929 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/ARMInstrThumb.td        |  2 +-
 lib/Target/MBlaze/MBlazeInstrInfo.td   | 18 ++++++++++--------
 lib/Target/SystemZ/SystemZInstrInfo.td |  2 +-
 lib/Target/X86/X86InstrInfo.td         |  2 +-
 utils/TableGen/CodeGenDAGPatterns.cpp  |  6 ++++++
 5 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/lib/Target/ARM/ARMInstrThumb.td b/lib/Target/ARM/ARMInstrThumb.td
index 4a7e6a1c6a8..3e81516726b 100644
--- a/lib/Target/ARM/ARMInstrThumb.td
+++ b/lib/Target/ARM/ARMInstrThumb.td
@@ -312,7 +312,7 @@ def tPICADD : TIt<(outs GPR:$dst), (ins GPR:$lhs, pclabel:$cp), IIC_iALUr, "",
 // ADD <Rd>, sp, #<imm8>
 // This is rematerializable, which is particularly useful for taking the
 // address of locals.
-let isReMaterializable = 1 in
+let isReMaterializable = 1, neverHasSideEffects = 1 in
 def tADDrSPi : T1pI<(outs tGPR:$dst), (ins GPRsp:$sp, t_imm0_1020s4:$imm),
                     IIC_iALUi, "add", "\t$dst, $sp, $imm", []>,
                T1Encoding<{1,0,1,0,1,?}> {
diff --git a/lib/Target/MBlaze/MBlazeInstrInfo.td b/lib/Target/MBlaze/MBlazeInstrInfo.td
index 43c1d52d8eb..1d8c987a085 100644
--- a/lib/Target/MBlaze/MBlazeInstrInfo.td
+++ b/lib/Target/MBlaze/MBlazeInstrInfo.td
@@ -442,17 +442,19 @@ let Predicates=[HasMul] in {
 //===----------------------------------------------------------------------===//
 
 let canFoldAsLoad = 1, isReMaterializable = 1 in {
-  def LBU  :  LoadM<0x30, 0x000, "lbu    ">;
-  def LBUR :  LoadM<0x30, 0x200, "lbur   ">;
+  let neverHasSideEffects = 1 in {
+    def LBU  :  LoadM<0x30, 0x000, "lbu    ">;
+    def LBUR :  LoadM<0x30, 0x200, "lbur   ">;
 
-  def LHU  :  LoadM<0x31, 0x000, "lhu    ">;
-  def LHUR :  LoadM<0x31, 0x200, "lhur   ">;
+    def LHU  :  LoadM<0x31, 0x000, "lhu    ">;
+    def LHUR :  LoadM<0x31, 0x200, "lhur   ">;
 
-  def LW   :  LoadM<0x32, 0x000, "lw     ">;
-  def LWR  :  LoadM<0x32, 0x200, "lwr    ">;
+    def LW   :  LoadM<0x32, 0x000, "lw     ">;
+    def LWR  :  LoadM<0x32, 0x200, "lwr    ">;
 
-  let Defs = [CARRY] in {
-    def LWX  :  LoadM<0x32, 0x400, "lwx    ">;
+    let Defs = [CARRY] in {
+      def LWX  :  LoadM<0x32, 0x400, "lwx    ">;
+    }
   }
 
   def LBUI : LoadMI<0x38, "lbui   ", zextloadi8>;
diff --git a/lib/Target/SystemZ/SystemZInstrInfo.td b/lib/Target/SystemZ/SystemZInstrInfo.td
index 11a39fcd023..580d65b27f8 100644
--- a/lib/Target/SystemZ/SystemZInstrInfo.td
+++ b/lib/Target/SystemZ/SystemZInstrInfo.td
@@ -478,7 +478,7 @@ def MOV64rmm  : RSYI<0x04EB,
                      "lmg\t{$from, $to, $dst}",
                      []>;
 
-let isReMaterializable = 1, isAsCheapAsAMove = 1,
+let isReMaterializable = 1, neverHasSideEffects = 1, isAsCheapAsAMove = 1,
     Constraints = "$src = $dst" in {
 def MOV64Pr0_even : Pseudo<(outs GR64P:$dst), (ins GR64P:$src),
                            "lhi\t${dst:subreg_even}, 0",
diff --git a/lib/Target/X86/X86InstrInfo.td b/lib/Target/X86/X86InstrInfo.td
index 506931e28de..c43351a0293 100644
--- a/lib/Target/X86/X86InstrInfo.td
+++ b/lib/Target/X86/X86InstrInfo.td
@@ -967,7 +967,7 @@ let mayStore = 1 in
 def MOV8mr_NOREX : I<0x88, MRMDestMem,
                      (outs), (ins i8mem_NOREX:$dst, GR8_NOREX:$src),
                      "mov{b}\t{$src, $dst|$dst, $src}  # NOREX", []>;
-let mayLoad = 1,
+let mayLoad = 1, neverHasSideEffects = 1,
     canFoldAsLoad = 1, isReMaterializable = 1 in
 def MOV8rm_NOREX : I<0x8A, MRMSrcMem,
                      (outs GR8_NOREX:$dst), (ins i8mem_NOREX:$src),
diff --git a/utils/TableGen/CodeGenDAGPatterns.cpp b/utils/TableGen/CodeGenDAGPatterns.cpp
index 4954f339869..dbf166262bb 100644
--- a/utils/TableGen/CodeGenDAGPatterns.cpp
+++ b/utils/TableGen/CodeGenDAGPatterns.cpp
@@ -2829,6 +2829,12 @@ void CodeGenDAGPatterns::InferInstructionFlags() {
     InstInfo.isBitcast = IsBitcast;
     InstInfo.hasSideEffects = HasSideEffects;
     InstInfo.Operands.isVariadic = IsVariadic;
+
+    // Sanity checks.
+    if (InstInfo.isReMaterializable && InstInfo.hasSideEffects)
+      throw TGError(InstInfo.TheDef->getLoc(), "The instruction " +
+                    InstInfo.TheDef->getName() +
+                    " is rematerializable AND has unmodeled side effects?");
   }
 }