From 52c39396151978ca946e2a80d9118c8672bace14 Mon Sep 17 00:00:00 2001
From: Momchil Velikov <momchil.velikov@arm.com>
Date: Wed, 17 Jul 2019 10:53:13 +0000
Subject: [PATCH] [TableGen] Do not set ReadNone attribute on intrinsics with
 side effects

If an intrinsic is defined without outputs, but having side effects,
it still can be removed completely from the program. This patch makes
TableGen not set Attribute::ReadNone for intrinsics which
are declared with IntrHasSideEffects.

Differential Revision: https://reviews.llvm.org/D64414

llvm-svn: 366312
---
 llvm/test/TableGen/intrin-side-effects.td  | 39 ++++++++++++++++++++++++++++++
 llvm/utils/TableGen/CodeGenDAGPatterns.cpp |  2 +-
 llvm/utils/TableGen/IntrinsicEmitter.cpp   |  4 ++-
 3 files changed, 43 insertions(+), 2 deletions(-)
 create mode 100644 llvm/test/TableGen/intrin-side-effects.td

diff --git a/llvm/test/TableGen/intrin-side-effects.td b/llvm/test/TableGen/intrin-side-effects.td
new file mode 100644
index 0000000..7588855
--- /dev/null
+++ b/llvm/test/TableGen/intrin-side-effects.td
@@ -0,0 +1,39 @@
+// RUN: llvm-tblgen -gen-intrinsic-impl -I %p/../../include %s | FileCheck %s
+
+// Get the minimum blurb necessary to process ...
+include "llvm/CodeGen/ValueTypes.td"
+include "llvm/CodeGen/SDNodeProperties.td"
+
+class LLVMType<ValueType vt> {
+  ValueType VT = vt;
+  int isAny = 0;
+}
+
+def llvm_i32_ty        : LLVMType<i32>;
+
+class IntrinsicProperty;
+def IntrNoMem : IntrinsicProperty;
+def IntrHasSideEffects : IntrinsicProperty;
+
+
+class Intrinsic<list<LLVMType> ret_types,
+                list<LLVMType> param_types = [],
+                list<IntrinsicProperty> intr_properties = [],
+                string name = "",
+                list<SDNodeProperty> sd_properties = []> : SDPatternOperator {
+  string LLVMName = name;
+  string TargetPrefix = "";
+  list<LLVMType> RetTypes = ret_types;
+  list<LLVMType> ParamTypes = param_types;
+  list<IntrinsicProperty> IntrProperties = intr_properties;
+  let Properties = sd_properties;
+
+  bit isTarget = 0;
+}
+
+// ... this intrinsic.
+def int_random_gen   : Intrinsic<[llvm_i32_ty], [], [IntrNoMem, IntrHasSideEffects]>;
+
+// CHECK: 1, // llvm.random.gen
+// CHECK: case 1:
+// CHECK-NEXT: Atts[] = {Attribute::NoUnwind}
diff --git a/llvm/utils/TableGen/CodeGenDAGPatterns.cpp b/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
index a0e8696..c8f710d 100644
--- a/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
+++ b/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
@@ -2807,7 +2807,7 @@ TreePatternNodePtr TreePattern::ParseTreePattern(Init *TheInit,
     // chain.
     if (Int.IS.RetVTs.empty())
       Operator = getDAGPatterns().get_intrinsic_void_sdnode();
-    else if (Int.ModRef != CodeGenIntrinsic::NoMem)
+    else if (Int.ModRef != CodeGenIntrinsic::NoMem || Int.hasSideEffects)
       // Has side-effects, requires chain.
       Operator = getDAGPatterns().get_intrinsic_w_chain_sdnode();
     else // Otherwise, no chain.
diff --git a/llvm/utils/TableGen/IntrinsicEmitter.cpp b/llvm/utils/TableGen/IntrinsicEmitter.cpp
index bcb8af2..6bcdc3d 100644
--- a/llvm/utils/TableGen/IntrinsicEmitter.cpp
+++ b/llvm/utils/TableGen/IntrinsicEmitter.cpp
@@ -685,7 +685,7 @@ void IntrinsicEmitter::EmitAttributes(const CodeGenIntrinsicTable &Ints,
     }
 
     if (!intrinsic.canThrow ||
-        intrinsic.ModRef != CodeGenIntrinsic::ReadWriteMem ||
+        (intrinsic.ModRef != CodeGenIntrinsic::ReadWriteMem && !intrinsic.hasSideEffects) ||
         intrinsic.isNoReturn || intrinsic.isCold || intrinsic.isNoDuplicate ||
         intrinsic.isConvergent || intrinsic.isSpeculatable) {
       OS << "      const Attribute::AttrKind Atts[] = {";
@@ -727,6 +727,8 @@ void IntrinsicEmitter::EmitAttributes(const CodeGenIntrinsicTable &Ints,
 
       switch (intrinsic.ModRef) {
       case CodeGenIntrinsic::NoMem:
+        if (intrinsic.hasSideEffects)
+          break;
         if (addComma)
           OS << ",";
         OS << "Attribute::ReadNone";
-- 
2.7.4