From fffe3634933471ee9805412ffa221080c9e9e8fd Mon Sep 17 00:00:00 2001
From: Eric Christopher <echristo@gmail.com>
Date: Fri, 11 Jan 2013 18:12:39 +0000
Subject: [PATCH] For inline asm:

- recognize string "{memory}" in the MI generation
- mark as mayload/maystore when there's a memory clobber constraint.

PR14859.

Patch by Krzysztof Parzyszek

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172228 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/MachineInstr.cpp                     |  6 +++++-
 lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp |  6 ++++++
 lib/CodeGen/SelectionDAG/TargetLowering.cpp      | 10 +++++++---
 test/CodeGen/Generic/inline-asm-mem-clobber.ll   | 21 +++++++++++++++++++++
 4 files changed, 39 insertions(+), 4 deletions(-)
 create mode 100644 test/CodeGen/Generic/inline-asm-mem-clobber.ll

diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp
index df82a17a2b2..8f7c5fd0224 100644
--- a/lib/CodeGen/MachineInstr.cpp
+++ b/lib/CodeGen/MachineInstr.cpp
@@ -1476,10 +1476,14 @@ void MachineInstr::print(raw_ostream &OS, const TargetMachine *TM) const {
     OS << " ";
     getOperand(InlineAsm::MIOp_AsmString).print(OS, TM);
 
-    // Print HasSideEffects, IsAlignStack
+    // Print HasSideEffects, MayLoad, MayStore, IsAlignStack
     unsigned ExtraInfo = getOperand(InlineAsm::MIOp_ExtraInfo).getImm();
     if (ExtraInfo & InlineAsm::Extra_HasSideEffects)
       OS << " [sideeffect]";
+    if (ExtraInfo & InlineAsm::Extra_MayLoad)
+      OS << " [mayload]";
+    if (ExtraInfo & InlineAsm::Extra_MayStore)
+      OS << " [maystore]";
     if (ExtraInfo & InlineAsm::Extra_IsAlignStack)
       OS << " [alignstack]";
     if (getInlineAsmDialect() == InlineAsm::AD_ATT)
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 599ef2c7cc9..4e07fd379cb 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -5948,6 +5948,10 @@ void SelectionDAGBuilder::visitInlineAsm(ImmutableCallSite CS) {
     // Compute the constraint code and ConstraintType to use.
     TLI.ComputeConstraintToUse(OpInfo, OpInfo.CallOperand, &DAG);
 
+    if (OpInfo.ConstraintType == TargetLowering::C_Memory &&
+        OpInfo.Type == InlineAsm::isClobber)
+      continue;
+
     // If this is a memory input, and if the operand is not indirect, do what we
     // need to to provide an address for the memory input.
     if (OpInfo.ConstraintType == TargetLowering::C_Memory &&
@@ -6051,6 +6055,8 @@ void SelectionDAGBuilder::visitInlineAsm(ImmutableCallSite CS) {
         ExtraInfo |= InlineAsm::Extra_MayLoad;
       else if (OpInfo.Type == InlineAsm::isOutput)
         ExtraInfo |= InlineAsm::Extra_MayStore;
+      else if (OpInfo.Type == InlineAsm::isClobber)
+        ExtraInfo |= (InlineAsm::Extra_MayLoad | InlineAsm::Extra_MayStore);
     }
   }
 
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index d2da9b728d2..35a11b40cae 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -3068,7 +3068,9 @@ PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI) const {
 
 TargetLowering::ConstraintType
 TargetLowering::getConstraintType(const std::string &Constraint) const {
-  if (Constraint.size() == 1) {
+  unsigned S = Constraint.size();
+
+  if (S == 1) {
     switch (Constraint[0]) {
     default: break;
     case 'r': return C_RegisterClass;
@@ -3097,9 +3099,11 @@ TargetLowering::getConstraintType(const std::string &Constraint) const {
     }
   }
 
-  if (Constraint.size() > 1 && Constraint[0] == '{' &&
-      Constraint[Constraint.size()-1] == '}')
+  if (S > 1 && Constraint[0] == '{' && Constraint[S-1] == '}') {
+    if (S == 8 && !Constraint.compare(1, 6, "memory", 6))  // "{memory}"
+      return C_Memory;
     return C_Register;
+  }
   return C_Unknown;
 }
 
diff --git a/test/CodeGen/Generic/inline-asm-mem-clobber.ll b/test/CodeGen/Generic/inline-asm-mem-clobber.ll
new file mode 100644
index 00000000000..e523d031dc6
--- /dev/null
+++ b/test/CodeGen/Generic/inline-asm-mem-clobber.ll
@@ -0,0 +1,21 @@
+; RUN: llc -O2 < %s | FileCheck %s
+
+@G = common global i32 0, align 4
+
+define i32 @foo(i8* %p) nounwind uwtable {
+entry:
+  %p.addr = alloca i8*, align 8
+  %rv = alloca i32, align 4
+  store i8* %p, i8** %p.addr, align 8
+  store i32 0, i32* @G, align 4
+  %0 = load i8** %p.addr, align 8
+; CHECK: blah
+  %1 = call i32 asm "blah", "=r,r,~{memory}"(i8* %0) nounwind
+; CHECK: @G
+  store i32 %1, i32* %rv, align 4
+  %2 = load i32* %rv, align 4
+  %3 = load i32* @G, align 4
+  %add = add nsw i32 %2, %3
+  ret i32 %add
+}
+
-- 
2.11.0