[PATCH] MergeFunc: Avoid invalid merge of functions using different range metadata

Björn Steinbrink bsteinbr at gmail.com
Sun Jun 8 10:37:15 PDT 2014


Hi dyatkovskiy,

Different range metadata can lead to different optimizations in later
passes, possibly breaking the semantics of the merged function. So range
metadata must be taken into consideration when comparing Load
instructions.

http://reviews.llvm.org/D4062

Files:
  lib/Transforms/IPO/MergeFunctions.cpp
  test/Transforms/MergeFunc/ranges.ll

Index: lib/Transforms/IPO/MergeFunctions.cpp
===================================================================
--- lib/Transforms/IPO/MergeFunctions.cpp
+++ lib/Transforms/IPO/MergeFunctions.cpp
@@ -325,6 +325,7 @@
   /// 6.1.Load: volatile (as boolean flag)
   /// 6.2.Load: alignment (as integer numbers)
   /// 6.3.Load: synch-scope (as integer numbers)
+  /// 6.4.Load: range metadata (as integer numbers)
   /// On this stage its better to see the code, since its not more than 10-15
   /// strings for particular instruction, and could change sometimes.
   int cmpOperation(const Instruction *L, const Instruction *R) const;
@@ -788,7 +789,11 @@
     if (int Res =
             cmpNumbers(LI->getOrdering(), cast<LoadInst>(R)->getOrdering()))
       return Res;
-    return cmpNumbers(LI->getSynchScope(), cast<LoadInst>(R)->getSynchScope());
+    if (int Res =
+            cmpNumbers(LI->getSynchScope(), cast<LoadInst>(R)->getSynchScope()))
+      return Res;
+    return cmpNumbers((uint64_t)LI->getMetadata(LLVMContext::MD_range),
+                      (uint64_t)cast<LoadInst>(R)->getMetadata(LLVMContext::MD_range));
   }
   if (const StoreInst *SI = dyn_cast<StoreInst>(L)) {
     if (int Res =
Index: test/Transforms/MergeFunc/ranges.ll
===================================================================
--- /dev/null
+++ test/Transforms/MergeFunc/ranges.ll
@@ -0,0 +1,41 @@
+; RUN: opt -mergefunc -S < %s | FileCheck %s
+define i1 @cmp_with_range(i8*, i8*) {
+entry-block:
+  %v1 = load i8* %0, !range !0
+  %v2 = load i8* %1, !range !0
+  %out = icmp eq i8 %v1, %v2
+  ret i1 %out
+}
+
+define i1 @cmp_no_range(i8*, i8*) {
+; CHECK-LABEL: @cmp_no_range
+; CHECK-NOT: call
+entry-block:
+  %v1 = load i8* %0
+  %v2 = load i8* %1
+  %out = icmp eq i8 %v1, %v2
+  ret i1 %out
+}
+
+define i1 @cmp_different_range(i8*, i8*) {
+; CHECK-LABEL: @cmp_different_range
+; CHECK-NOT: call
+entry-block:
+  %v1 = load i8* %0, !range !1
+  %v2 = load i8* %1, !range !1
+  %out = icmp eq i8 %v1, %v2
+  ret i1 %out
+}
+
+define i1 @cmp_with_same_range(i8*, i8*) {
+; CHECK-LABEL: @cmp_with_same_range
+; CHECK: call i1 @cmp_with_range
+entry-block:
+  %v1 = load i8* %0, !range !0
+  %v2 = load i8* %1, !range !0
+  %out = icmp eq i8 %v1, %v2
+  ret i1 %out
+}
+
+!0 = metadata !{i8 0, i8 2}
+!1 = metadata !{i8 5, i8 7}
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