[SafepointIRVerifier] Add verifier pass for finding GC relocation bugs

Original Patch and summary by Philip Reames.

RewriteStatepointsForGC tries to rewrite a function in a manner where
the optimizer can't end up using a pointer value after it might have
been relocated by a safepoint. This pass checks the invariant that
RSForGC is supposed to establish and that (if we constructed semantics
correctly) later passes must preserve.

This has been a really useful diagnostic tool when initially developing
the rewriting scheme and has found numerous bugs.

Differential Revision: https://reviews.llvm.org/D15940

Reviewed by: swaroop.sridhar, mjacob

Subscribers: llvm-commits
llvm-svn: 307112

4 files changed, 242 insertions, 0 deletions

diff --git a/llvm/test/SafepointIRVerifier/basic-use-after-reloc.ll b/llvm/test/SafepointIRVerifier/basic-use-after-reloc.ll
new file mode 100644
index 0000000..4b0746c
--- /dev/null
+++ b/llvm/test/SafepointIRVerifier/basic-use-after-reloc.ll
@@ -0,0 +1,23 @@
+; RUN: opt -safepoint-ir-verifier-print-only -verify-safepoint-ir -S %s 2>&1 | FileCheck %s
+
+; This test checks that if a value is used immediately after a
+; safepoint without using the relocated value that the verifier
+; catches this.
+
+%jObject = type { [8 x i8] }
+
+; Function Attrs: nounwind
+define %jObject addrspace(1)* @test(%jObject addrspace(1)* %arg) gc "statepoint-example" {
+bci_0:
+  %safepoint_token3 = tail call token (i64, i32, double (double)*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_f64f64f(i64 0, i32 0, double (double)* undef, i32 1, i32 0, double undef, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0, %jObject addrspace(1)* %arg)
+  %arg2.relocated4 = call coldcc %jObject addrspace(1)* @llvm.experimental.gc.relocate.p1jObject(token %safepoint_token3, i32 13, i32 13)
+  ret %jObject addrspace(1)* %arg
+; CHECK: Illegal use of unrelocated value found!
+; CHECK-NEXT: Def: %jObject addrspace(1)* %arg
+; CHECK-NEXT: Use:   ret %jObject addrspace(1)* %arg
+}
+
+; Function Attrs: nounwind
+declare %jObject addrspace(1)* @llvm.experimental.gc.relocate.p1jObject(token, i32, i32) #3
+
+declare token @llvm.experimental.gc.statepoint.p0f_f64f64f(i64, i32, double (double)*, i32, i32, ...)
diff --git a/llvm/test/SafepointIRVerifier/constant-bases.ll b/llvm/test/SafepointIRVerifier/constant-bases.ll
new file mode 100644
index 0000000..52a2a46
--- /dev/null
+++ b/llvm/test/SafepointIRVerifier/constant-bases.ll
@@ -0,0 +1,70 @@
+; RUN: opt -safepoint-ir-verifier-print-only -verify-safepoint-ir -S %s 2>&1 | FileCheck %s
+
+define i8 addrspace(1)* @test1(i64 %arg) gc "statepoint-example" {
+; CHECK: No illegal uses found by SafepointIRVerifier in: test1
+entry:
+  %safepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* undef, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
+  ret i8 addrspace(1)* null
+}
+
+define i8 addrspace(1)* @test2(i64 %arg) gc "statepoint-example" {
+; CHECK: No illegal uses found by SafepointIRVerifier in: test2
+entry:
+  %load_addr = getelementptr i8, i8 addrspace(1)* inttoptr (i64 15 to i8 addrspace(1)*), i64 %arg
+  %safepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* undef, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
+  ret i8 addrspace(1)* %load_addr
+}
+
+define i8 addrspace(1)* @test3(i64 %arg) gc "statepoint-example" {
+; CHECK: No illegal uses found by SafepointIRVerifier in: test3
+entry:
+  %load_addr = getelementptr i32, i32 addrspace(1)* inttoptr (i64 15 to i32 addrspace(1)*), i64 %arg
+  %load_addr.cast = bitcast i32 addrspace(1)* %load_addr to i8 addrspace(1)*
+  %safepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* undef, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
+  ret i8 addrspace(1)* %load_addr.cast
+}
+
+define i8 addrspace(1)* @test4(i64 %arg, i1 %cond) gc "statepoint-example" {
+; CHECK: No illegal uses found by SafepointIRVerifier in: test4
+entry:
+  %load_addr.1 = getelementptr i8, i8 addrspace(1)* inttoptr (i64 15 to i8 addrspace(1)*), i64 %arg
+  br i1 %cond, label %split, label %join
+
+split:
+  %load_addr.2 = getelementptr i8, i8 addrspace(1)* inttoptr (i64 30 to i8 addrspace(1)*), i64 %arg
+  br label %join
+
+join:
+  %load_addr = phi i8 addrspace(1)* [%load_addr.1, %entry], [%load_addr.2, %split]
+  %safepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* undef, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
+  ret i8 addrspace(1)* %load_addr
+}
+
+define i8 addrspace(1)* @test5(i64 %arg, i1 %cond) gc "statepoint-example" {
+; CHECK: No illegal uses found by SafepointIRVerifier in: test5
+entry:
+  %load_addr.1 = getelementptr i8, i8 addrspace(1)* inttoptr (i64 15 to i8 addrspace(1)*), i64 %arg
+  %load_addr.2 = getelementptr i8, i8 addrspace(1)* inttoptr (i64 30 to i8 addrspace(1)*), i64 %arg
+  %load_addr = select i1 %cond, i8 addrspace(1)* %load_addr.1, i8 addrspace(1)* %load_addr.2
+  %safepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* undef, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
+  ret i8 addrspace(1)* %load_addr
+}
+
+define i8 addrspace(1)* @test6(i64 %arg, i1 %cond, i8 addrspace(1)* %base) gc "statepoint-example" {
+; CHECK-LABEL: Verifying gc pointers in function: test6
+; CHECK: Illegal use of unrelocated value found!
+entry:
+  %load_addr.1 = getelementptr i8, i8 addrspace(1)* %base, i64 %arg
+  br i1 %cond, label %split, label %join
+
+split:
+  %load_addr.2 = getelementptr i8, i8 addrspace(1)* inttoptr (i64 30 to i8 addrspace(1)*), i64 %arg
+  br label %join
+
+join:
+  %load_addr = phi i8 addrspace(1)* [%load_addr.1, %entry], [%load_addr.2, %split]
+  %safepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* undef, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
+  ret i8 addrspace(1)* %load_addr
+}
+
+declare token @llvm.experimental.gc.statepoint.p0f_isVoidf(i64, i32, void ()*, i32, i32, ...)
diff --git a/llvm/test/SafepointIRVerifier/unrecorded-live-at-sp.ll b/llvm/test/SafepointIRVerifier/unrecorded-live-at-sp.ll
new file mode 100644
index 0000000..e3f21c3
--- /dev/null
+++ b/llvm/test/SafepointIRVerifier/unrecorded-live-at-sp.ll
@@ -0,0 +1,71 @@
+; RUN: opt %s -safepoint-ir-verifier-print-only -verify-safepoint-ir -S 2>&1 | FileCheck %s
+
+; CHECK:      Illegal use of unrelocated value found!
+; CHECK-NEXT: Def:   %base_phi3 = phi %jObject addrspace(1)* [ %obj609.relocated, %not_zero146 ], [ %base_phi2, %bci_37-aload ], !is_base_value !0
+; CHECK-NEXT: Use:   %base_phi2 = phi %jObject addrspace(1)* [ %base_phi3, %not_zero179 ], [ %cast5, %bci_0 ], !is_base_value !0
+
+%jObject = type { [8 x i8] }
+
+declare %jObject addrspace(1)* @generate_obj1() #1
+
+declare %jObject addrspace(1)* addrspace(1)* @generate_obj2() #1
+
+declare %jObject addrspace(1)* @generate_obj3() #1
+
+; Function Attrs: nounwind
+define  void @test(%jObject addrspace(1)*, %jObject addrspace(1)*, i32) #3 gc "statepoint-example" {
+bci_0:
+  %result608 = call %jObject addrspace(1)* @generate_obj3()
+  %obj609 = bitcast %jObject addrspace(1)* %result608 to %jObject addrspace(1)*
+  %cast = bitcast %jObject addrspace(1)* %result608 to %jObject addrspace(1)*
+  %cast5 = bitcast %jObject addrspace(1)* %result608 to %jObject addrspace(1)*
+  br label %bci_37-aload
+
+bci_37-aload:                                     ; preds = %not_zero179, %bci_0
+  %base_phi = phi %jObject addrspace(1)* [ %base_phi1.relocated, %not_zero179 ], [ %cast, %bci_0 ], !is_base_value !0
+  %base_phi2 = phi %jObject addrspace(1)* [ %base_phi3, %not_zero179 ], [ %cast5, %bci_0 ], !is_base_value !0
+  %relocated8 = phi %jObject addrspace(1)* [ %relocated7.relocated, %not_zero179 ], [ %obj609, %bci_0 ]
+  %tmp3 = getelementptr inbounds %jObject, %jObject addrspace(1)* %relocated8, i64 0, i32 0, i64 32
+  %addr98 = bitcast i8 addrspace(1)* %tmp3 to %jObject addrspace(1)* addrspace(1)*
+  %cast6 = bitcast %jObject addrspace(1)* %base_phi2 to %jObject addrspace(1)* addrspace(1)*
+  br i1 undef, label %not_zero179, label %not_zero146
+
+not_zero146:                                      ; preds = %bci_37-aload
+  %addr98.relocated = call %jObject addrspace(1)* addrspace(1)* @generate_obj2() #1
+  %obj609.relocated = call %jObject addrspace(1)* @generate_obj1() #1
+  br label %not_zero179
+
+not_zero179:                                      ; preds = %not_zero146, %bci_37-aload
+  %base_phi1 = phi %jObject addrspace(1)* [ %obj609.relocated, %not_zero146 ], [ %base_phi, %bci_37-aload ], !is_base_value !0
+  %base_phi3 = phi %jObject addrspace(1)* [ %obj609.relocated, %not_zero146 ], [ %base_phi2, %bci_37-aload ], !is_base_value !0
+  %relocated7 = phi %jObject addrspace(1)* [ %obj609.relocated, %not_zero146 ], [ %relocated8, %bci_37-aload ]
+  %base_phi4 = phi %jObject addrspace(1)* addrspace(1)* [ %addr98.relocated, %not_zero146 ], [ %cast6, %bci_37-aload ], !is_base_value !0
+  %relocated4 = phi %jObject addrspace(1)* addrspace(1)* [ %addr98.relocated, %not_zero146 ], [ %addr98, %bci_37-aload ]
+  %safepoint_token = tail call  token (i64, i32, i32 ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_i32f(i64 0, i32 0, i32 ()* undef, i32 0, i32 0, i32 0, i32 5, i32 0, i32 0, i32 0, i32 0, i32 0, %jObject addrspace(1)* %base_phi1, %jObject addrspace(1)* addrspace(1)* %base_phi4, %jObject addrspace(1)* addrspace(1)* %relocated4, %jObject addrspace(1)* %relocated7)
+  %tmp4 = call i32 @llvm.experimental.gc.result.i32(token %safepoint_token)
+  %base_phi1.relocated = call coldcc %jObject addrspace(1)* @llvm.experimental.gc.relocate.p1jObject(token %safepoint_token, i32 12, i32 12)
+  %base_phi4.relocated = call coldcc %jObject addrspace(1)* addrspace(1)* @llvm.experimental.gc.relocate.p1p1jObject(token %safepoint_token, i32 13, i32 13)
+  %relocated4.relocated = call coldcc %jObject addrspace(1)* addrspace(1)* @llvm.experimental.gc.relocate.p1p1jObject(token %safepoint_token, i32 13, i32 14)
+  %relocated7.relocated = call coldcc %jObject addrspace(1)* @llvm.experimental.gc.relocate.p1jObject(token %safepoint_token, i32 12, i32 15)
+  %addr636 = bitcast %jObject addrspace(1)* addrspace(1)* %relocated4.relocated to %jObject addrspace(1)* addrspace(1)*
+  br label %bci_37-aload
+}
+
+declare token @llvm.experimental.gc.statepoint.p0f_i32f(i64, i32, i32 ()*, i32, i32, ...)
+
+; Function Attrs: nounwind
+declare i32 @llvm.experimental.gc.result.i32(token) #4
+
+; Function Attrs: nounwind
+declare %jObject addrspace(1)* @llvm.experimental.gc.relocate.p1jObject(token, i32, i32) #4
+
+; Function Attrs: nounwind
+declare %jObject addrspace(1)* addrspace(1)* @llvm.experimental.gc.relocate.p1p1jObject(token, i32, i32) #4
+
+attributes #0 = { noinline nounwind "gc-leaf-function"="true" }
+attributes #1 = { "gc-leaf-function"="true" }
+attributes #2 = { nounwind readonly "gc-leaf-function"="true" }
+attributes #3 = { nounwind }
+attributes #4 = { nounwind }
+
+!0 = !{i32 1}
diff --git a/llvm/test/SafepointIRVerifier/uses-in-phi-nodes.ll b/llvm/test/SafepointIRVerifier/uses-in-phi-nodes.ll
new file mode 100644
index 0000000..d06eb6e0
--- /dev/null
+++ b/llvm/test/SafepointIRVerifier/uses-in-phi-nodes.ll
@@ -0,0 +1,78 @@
+; RUN: opt -safepoint-ir-verifier-print-only -verify-safepoint-ir -S %s 2>&1 | FileCheck %s
+
+define i8 addrspace(1)* @test.not.ok.0(i8 addrspace(1)* %arg) gc "statepoint-example" {
+; CHECK-LABEL: Verifying gc pointers in function: test.not.ok.0
+ bci_0:
+  br i1 undef, label %left, label %right
+
+ left:
+  %safepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* undef, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
+  br label %merge
+
+ right:
+  br label %merge
+
+ merge:
+; CHECK: Illegal use of unrelocated value found!
+; CHECK-NEXT: Def: i8 addrspace(1)* %arg
+; CHECK-NEXT: Use:   %val = phi i8 addrspace(1)* [ %arg, %left ], [ %arg, %right ]
+  %val = phi i8 addrspace(1)* [ %arg, %left ], [ %arg, %right]
+  ret i8 addrspace(1)* %val
+}
+
+define i8 addrspace(1)* @test.not.ok.1(i8 addrspace(1)* %arg) gc "statepoint-example" {
+; CHECK-LABEL: Verifying gc pointers in function: test.not.ok.1
+ bci_0:
+  br i1 undef, label %left, label %right
+
+ left:
+  %safepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* undef, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
+  br label %merge
+
+ right:
+  br label %merge
+
+ merge:
+; CHECK: Illegal use of unrelocated value found!
+; CHECK-NEXT: Def: i8 addrspace(1)* %arg
+; CHECK-NEXT: Use:   %val = phi i8 addrspace(1)* [ %arg, %left ], [ null, %right ]
+  %val = phi i8 addrspace(1)* [ %arg, %left ], [ null, %right]
+  ret i8 addrspace(1)* %val
+}
+
+define i8 addrspace(1)* @test.ok.0(i8 addrspace(1)* %arg) gc "statepoint-example" {
+; CHECK: No illegal uses found by SafepointIRVerifier in: test.ok.0
+ bci_0:
+  br i1 undef, label %left, label %right
+
+ left:
+  %safepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* undef, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
+  br label %merge
+
+ right:
+  br label %merge
+
+ merge:
+  %val = phi i8 addrspace(1)* [ null, %left ], [ null, %right]
+  ret i8 addrspace(1)* %val
+}
+
+define i8 addrspace(1)* @test.ok.1(i8 addrspace(1)* %arg) gc "statepoint-example" {
+; CHECK: No illegal uses found by SafepointIRVerifier in: test.ok.1
+ bci_0:
+  br i1 undef, label %left, label %right
+
+ left:
+  call void @not_statepoint()
+  br label %merge
+
+ right:
+  br label %merge
+
+ merge:
+  %val = phi i8 addrspace(1)* [ %arg, %left ], [ %arg, %right]
+  ret i8 addrspace(1)* %val
+}
+
+declare token @llvm.experimental.gc.statepoint.p0f_isVoidf(i64, i32, void ()*, i32, i32, ...)
+declare void @not_statepoint()