From 01841ea1ce9afda895f26dcdb2f74994f52ed35c Mon Sep 17 00:00:00 2001
From: Alexander Musman <alexander.musman@gmail.com>
Date: Mon, 21 Sep 2015 14:41:00 +0000
Subject: [PATCH] Fix assertion in inline assembler IR gen Several inputs may
 not refer to one output constraint in inline assembler insertions, clang was
 failing on assertion on such test case.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@248158 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/clang/Basic/DiagnosticSemaKinds.td |  4 ++++
 lib/Sema/SemaStmtAsm.cpp                   | 15 +++++++++++++++
 test/Sema/asm.c                            | 12 ++++++++++++
 3 files changed, 31 insertions(+)

diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 3432b6c268..67e629f29e 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -6418,6 +6418,8 @@ let CategoryName = "Inline Assembly Issue" in {
   def err_asm_non_addr_value_in_memory_constraint : Error <
     "reference to a %select{bit-field|vector element|global register variable}0"
     " in asm %select{input|output}1 with a memory constraint '%2'">;
+  def err_asm_input_duplicate_match : Error<
+    "more than one input constraint matches the same output '%0'">;
 
   def warn_asm_label_on_auto_decl : Warning<
     "ignored asm label '%0' on automatic variable">;
@@ -6432,6 +6434,8 @@ let CategoryName = "Inline Assembly Issue" in {
 
   def note_asm_missing_constraint_modifier : Note<
     "use constraint modifier \"%0\"">;
+  def note_asm_input_duplicate_first : Note<
+    "constraint '%0' is already present here">;
 }
 
 let CategoryName = "Semantic Issue" in {
diff --git a/lib/Sema/SemaStmtAsm.cpp b/lib/Sema/SemaStmtAsm.cpp
index b148cc9c76..79c06367e0 100644
--- a/lib/Sema/SemaStmtAsm.cpp
+++ b/lib/Sema/SemaStmtAsm.cpp
@@ -420,6 +420,8 @@ StmtResult Sema::ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
                             diag::err_asm_unexpected_constraint_alternatives)
                        << NumAlternatives << AltCount);
   }
+  SmallVector<size_t, 4> InputMatchedToOutput(OutputConstraintInfos.size(),
+                                              ~0U);
   for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
     TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
     StringRef ConstraintStr = Info.getConstraintStr();
@@ -441,6 +443,19 @@ StmtResult Sema::ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
     Expr *OutputExpr = Exprs[TiedTo];
     Expr *InputExpr = Exprs[InputOpNo];
 
+    // Make sure no more than one input constraint matches each output.
+    assert(TiedTo < InputMatchedToOutput.size() && "TiedTo value out of range");
+    if (InputMatchedToOutput[TiedTo] != ~0U) {
+      Diag(NS->getInputExpr(i)->getLocStart(),
+           diag::err_asm_input_duplicate_match)
+          << TiedTo;
+      Diag(NS->getInputExpr(InputMatchedToOutput[TiedTo])->getLocStart(),
+           diag::note_asm_input_duplicate_first)
+          << TiedTo;
+      return StmtError();
+    }
+    InputMatchedToOutput[TiedTo] = i;
+
     if (OutputExpr->isTypeDependent() || InputExpr->isTypeDependent())
       continue;
 
diff --git a/test/Sema/asm.c b/test/Sema/asm.c
index 9ed8d843ea..76e20158c4 100644
--- a/test/Sema/asm.c
+++ b/test/Sema/asm.c
@@ -236,3 +236,15 @@ void test16()
           : "m" (test16_baz)); // expected-error {{reference to a global register variable in asm output with a memory constraint 'm'}}
 }
 
+int test17(int t0)
+{
+  int r0, r1;
+  __asm ("addl %2, %2\n\t"
+         "movl $123, %0"
+         : "=a" (r0),
+           "=&r" (r1)
+         : "1" (t0),   // expected-note {{constraint '1' is already present here}}
+           "1" (t0));  // expected-error {{more than one input constraint matches the same output '1'}}
+  return r0 + r1;
+}
+
-- 
2.50.1