[PATCH] D48721: Patch to fix pragma metadata for do-while loops

[Deepak Panickal via Phabricator via cfe-commits]

deepak2427 updated this revision to Diff 154244.
deepak2427 added a comment.

Updated with test from Bjorn Pettersson which is much more accurate and clearer. Thanks!


https://reviews.llvm.org/D48721

Files:
  lib/CodeGen/CGStmt.cpp
  test/CodeGen/pragma-do-while.cpp


Index: test/CodeGen/pragma-do-while.cpp
===================================================================
--- /dev/null
+++ test/CodeGen/pragma-do-while.cpp
@@ -0,0 +1,36 @@
+// RUN: %clang_cc1 -emit-llvm %s -o - | FileCheck %s
+
+// We expect to get a loop structure like this:
+//    do.body:                                       ; preds = %do.cond, ...
+//      ...
+//      br label %do.cond
+//    do.cond:                                       ; preds = %do.body
+//      ...
+//      br i1 %cmp, label %do.body, label %do.end
+//    do.end:                                        ; preds = %do.cond
+//      ...
+//
+// Verify that the loop metadata only is put on the backedge.
+//
+// CHECK-NOT: llvm.loop
+// CHECK-LABEL: do.cond:
+// CHECK: br {{.*}}, label %do.body, label %do.end, !llvm.loop ![[LMD1:[0-9]+]]
+// CHECK-LABEL: do.end:
+// CHECK-NOT: llvm.loop
+// CHECK: ![[LMD1]] = distinct !{![[LMD1]], ![[LMD2:[0-9]+]]}
+// CHECK: ![[LMD2]] = !{!"llvm.loop.unroll.count", i32 4}
+
+int test(int a[], int n) {
+  int i = 0;
+  int sum = 0;
+
+#pragma unroll 4
+  do
+  {
+    a[i] = a[i] + 1;
+    sum = sum + a[i];
+    i++;
+  } while (i < n);
+
+  return sum;
+}
Index: lib/CodeGen/CGStmt.cpp
===================================================================
--- lib/CodeGen/CGStmt.cpp
+++ lib/CodeGen/CGStmt.cpp
@@ -777,19 +777,19 @@
   // Emit the body of the loop.
   llvm::BasicBlock *LoopBody = createBasicBlock("do.body");
 
-  const SourceRange &R = S.getSourceRange();
-  LoopStack.push(LoopBody, CGM.getContext(), DoAttrs,
-                 SourceLocToDebugLoc(R.getBegin()),
-                 SourceLocToDebugLoc(R.getEnd()));
-
   EmitBlockWithFallThrough(LoopBody, &S);
   {
     RunCleanupsScope BodyScope(*this);
     EmitStmt(S.getBody());
   }
 
   EmitBlock(LoopCond.getBlock());
 
+  const SourceRange &R = S.getSourceRange();
+  LoopStack.push(LoopBody, CGM.getContext(), DoAttrs,
+                 SourceLocToDebugLoc(R.getBegin()),
+                 SourceLocToDebugLoc(R.getEnd()));
+
   // C99 6.8.5.2: "The evaluation of the controlling expression takes place
   // after each execution of the loop body."
 


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