[PATCH] D14306: [CaptureTracking] Support operand bundles conservatively

[Sanjoy Das via llvm-commits]

sanjoy created this revision.
sanjoy added reviewers: reames, majnemer.
sanjoy added a subscriber: llvm-commits.

Earlier CaptureTracking would assume all "interesting" operands to a
call or invoke were its arguments.  With operand bundles this is no
longer true.

Note: an earlier change got `doesNotCapture` working correctly with
operand bundles.

This change uses DSE to test the changes to CaptureTracking.  DSE is a
vehicle for testing only, and is not directly involved in this change.

http://reviews.llvm.org/D14306

Files:
  lib/Analysis/CaptureTracking.cpp
  test/Feature/OperandBundles/dse.ll

Index: test/Feature/OperandBundles/dse.ll
===================================================================
--- /dev/null
+++ test/Feature/OperandBundles/dse.ll
@@ -0,0 +1,29 @@
+; RUN: opt -S -dse < %s | FileCheck %s
+
+declare void @f()
+declare noalias i8* @malloc(i32) nounwind
+
+define void @test_0() {
+; CHECK-LABEL: @test_0(
+  %m = call i8* @malloc(i32 24)
+  tail call void @f() [ "unknown"(i8* %m) ]
+; CHECK: store i8 -19, i8* %m
+  store i8 -19, i8* %m
+  ret void
+}
+
+define i8* @test_1() {
+; CHECK-LABEL: @test_1(
+  %m = call i8* @malloc(i32 24)
+  tail call void @f() [ "unknown"(i8* %m) ]
+  store i8 -19, i8* %m
+  tail call void @f()
+  store i8 101, i8* %m
+
+; CHECK: tail call void @f() [ "unknown"(i8* %m) ]
+; CHECK: store i8 -19, i8* %m
+; CHECK: tail call void @f()
+; CHECK: store i8 101, i8* %m
+
+  ret i8* %m
+}
Index: lib/Analysis/CaptureTracking.cpp
===================================================================
--- lib/Analysis/CaptureTracking.cpp
+++ lib/Analysis/CaptureTracking.cpp
@@ -253,7 +253,7 @@
       // that loading a value from a pointer does not cause the pointer to be
       // captured, even though the loaded value might be the pointer itself
       // (think of self-referential objects).
-      CallSite::arg_iterator B = CS.arg_begin(), E = CS.arg_end();
+      CallSite::arg_iterator B = CS.param_begin(), E = CS.param_end();
       for (CallSite::arg_iterator A = B; A != E; ++A)
         if (A->get() == V && !CS.doesNotCapture(A - B))
           // The parameter is not marked 'nocapture' - captured.


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