[llvm] 7df2eba - [Attributor][OpenMP] Add assumption for non-call assembly instructions
Johannes Doerfert via llvm-commits
llvm-commits at lists.llvm.org
Mon Mar 28 18:58:49 PDT 2022
Author: Johannes Doerfert
Date: 2022-03-28T20:57:52-05:00
New Revision: 7df2eba7fac2281498092dedea67d85d4f7ecfd5
URL: https://github.com/llvm/llvm-project/commit/7df2eba7fac2281498092dedea67d85d4f7ecfd5
DIFF: https://github.com/llvm/llvm-project/commit/7df2eba7fac2281498092dedea67d85d4f7ecfd5.diff
LOG: [Attributor][OpenMP] Add assumption for non-call assembly instructions
Inline assembly is scary but we need to support it for the OpenMP GPU
device runtime. The new assumption expresses the fact that it may not
have call semantics, that is, it will not call another function but
simply perform an operation or side-effect. This is important for
reachability in the presence of inline assembly.
Differential Revision: https://reviews.llvm.org/D109986
Added:
llvm/test/Transforms/Attributor/reachability.ll
Modified:
llvm/include/llvm/IR/Assumptions.h
llvm/lib/IR/Assumptions.cpp
llvm/lib/Transforms/IPO/AttributorAttributes.cpp
openmp/libomptarget/DeviceRTL/include/Types.h
Removed:
################################################################################
diff --git a/llvm/include/llvm/IR/Assumptions.h b/llvm/include/llvm/IR/Assumptions.h
index 08e6c8b6f1e0a..2d2ecfbde6e6b 100644
--- a/llvm/include/llvm/IR/Assumptions.h
+++ b/llvm/include/llvm/IR/Assumptions.h
@@ -34,6 +34,10 @@ extern StringSet<> KnownAssumptionStrings;
/// Helper that allows to insert a new assumption string in the known assumption
/// set by creating a (static) object.
struct KnownAssumptionString {
+ KnownAssumptionString(const char *AssumptionStr)
+ : AssumptionStr(AssumptionStr) {
+ KnownAssumptionStrings.insert(AssumptionStr);
+ }
KnownAssumptionString(StringRef AssumptionStr)
: AssumptionStr(AssumptionStr) {
KnownAssumptionStrings.insert(AssumptionStr);
diff --git a/llvm/lib/IR/Assumptions.cpp b/llvm/lib/IR/Assumptions.cpp
index 3d24ae062841e..27977d5d56b0d 100644
--- a/llvm/lib/IR/Assumptions.cpp
+++ b/llvm/lib/IR/Assumptions.cpp
@@ -107,4 +107,5 @@ StringSet<> llvm::KnownAssumptionStrings({
"omp_no_openmp_routines", // OpenMP 5.1
"omp_no_parallelism", // OpenMP 5.1
"ompx_spmd_amenable", // OpenMPOpt extension
+ "ompx_no_call_asm", // OpenMPOpt extension
});
diff --git a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
index 9328e7eb44c45..61eb0e43700d4 100644
--- a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
+++ b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
@@ -32,6 +32,7 @@
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/Argument.h"
#include "llvm/IR/Assumptions.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
@@ -9540,7 +9541,9 @@ struct AACallEdgesCallSite : public AACallEdgesImpl {
CallBase *CB = cast<CallBase>(getCtxI());
if (CB->isInlineAsm()) {
- setHasUnknownCallee(false, Change);
+ if (!hasAssumption(*CB->getCaller(), "ompx_no_call_asm") &&
+ !hasAssumption(*CB, "ompx_no_call_asm"))
+ setHasUnknownCallee(false, Change);
return Change;
}
diff --git a/llvm/test/Transforms/Attributor/reachability.ll b/llvm/test/Transforms/Attributor/reachability.ll
new file mode 100644
index 0000000000000..989fd4920554b
--- /dev/null
+++ b/llvm/test/Transforms/Attributor/reachability.ll
@@ -0,0 +1,49 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature --check-attributes --check-globals
+; RUN: opt -attributor -enable-new-pm=0 -attributor-manifest-internal -attributor-max-iterations-verify -attributor-annotate-decl-cs -attributor-max-iterations=2 -S < %s | FileCheck %s --check-prefixes=CHECK,NOT_CGSCC_NPM,NOT_CGSCC_OPM,NOT_TUNIT_NPM,IS__TUNIT____,IS________OPM,IS__TUNIT_OPM
+; RUN: opt -aa-pipeline=basic-aa -passes=attributor -attributor-manifest-internal -attributor-max-iterations-verify -attributor-annotate-decl-cs -attributor-max-iterations=2 -S < %s | FileCheck %s --check-prefixes=CHECK,NOT_CGSCC_OPM,NOT_CGSCC_NPM,NOT_TUNIT_OPM,IS__TUNIT____,IS________NPM,IS__TUNIT_NPM
+; RUN: opt -attributor-cgscc -enable-new-pm=0 -attributor-manifest-internal -attributor-annotate-decl-cs -S < %s | FileCheck %s --check-prefixes=CHECK,NOT_TUNIT_NPM,NOT_TUNIT_OPM,NOT_CGSCC_NPM,IS__CGSCC____,IS________OPM,IS__CGSCC_OPM
+; RUN: opt -aa-pipeline=basic-aa -passes=attributor-cgscc -attributor-manifest-internal -attributor-annotate-decl-cs -S < %s | FileCheck %s --check-prefixes=CHECK,NOT_TUNIT_NPM,NOT_TUNIT_OPM,NOT_CGSCC_OPM,IS__CGSCC____,IS________NPM,IS__CGSCC_NPM
+
+define void @non_recursive_asm_fn() #0 {
+; CHECK: Function Attrs: norecurse
+; CHECK-LABEL: define {{[^@]+}}@non_recursive_asm_fn
+; CHECK-SAME: () #[[ATTR0:[0-9]+]] {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: call void asm sideeffect "barrier.sync $0
+; CHECK-NEXT: ret void
+;
+entry:
+ call void asm sideeffect "barrier.sync $0;", "r,~{memory},~{dirflag},~{fpsr},~{flags}"(i32 1)
+ ret void
+}
+
+define void @non_recursive_asm_cs() {
+; CHECK: Function Attrs: norecurse
+; CHECK-LABEL: define {{[^@]+}}@non_recursive_asm_cs
+; CHECK-SAME: () #[[ATTR1:[0-9]+]] {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: call void asm sideeffect "barrier.sync $0
+; CHECK-NEXT: ret void
+;
+entry:
+ call void asm sideeffect "barrier.sync $0;", "r,~{memory},~{dirflag},~{fpsr},~{flags}"(i32 1) #0
+ ret void
+}
+
+define void @recursive_asm() {
+; CHECK-LABEL: define {{[^@]+}}@recursive_asm() {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: call void asm sideeffect "barrier.sync $0
+; CHECK-NEXT: ret void
+;
+entry:
+ call void asm sideeffect "barrier.sync $0;", "r,~{memory},~{dirflag},~{fpsr},~{flags}"(i32 1)
+ ret void
+}
+
+attributes #0 = { "llvm.assume"="ompx_no_call_asm" }
+;.
+; CHECK: attributes #[[ATTR0]] = { norecurse "llvm.assume"="ompx_no_call_asm" }
+; CHECK: attributes #[[ATTR1]] = { norecurse }
+; CHECK: attributes #[[ATTR2:[0-9]+]] = { "llvm.assume"="ompx_no_call_asm" }
+;.
diff --git a/openmp/libomptarget/DeviceRTL/include/Types.h b/openmp/libomptarget/DeviceRTL/include/Types.h
index 0ff0cee66b3f3..34f3e924a3a26 100644
--- a/openmp/libomptarget/DeviceRTL/include/Types.h
+++ b/openmp/libomptarget/DeviceRTL/include/Types.h
@@ -12,6 +12,15 @@
#ifndef OMPTARGET_TYPES_H
#define OMPTARGET_TYPES_H
+// Tell the compiler that we do not have any "call-like" inline assembly in the
+// device rutime. That means we cannot have inline assembly which will call
+// another function but only inline assembly that performs some operation or
+// side-effect and then continues execution with something on the existing call
+// stack.
+//
+// TODO: Find a good place for this
+#pragma omp assumes ext_no_call_asm
+
/// Base type declarations for freestanding mode
///
///{
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