[llvm] 752fea7 - [SCCP] Add range metadata to call sites with known return ranges.
Florian Hahn via llvm-commits
llvm-commits at lists.llvm.org
Tue Jul 21 02:14:20 PDT 2020
Author: Florian Hahn
Date: 2020-07-21T10:06:54+01:00
New Revision: 752fea7c27b66b7d34925335541f843eb46f16d6
URL: https://github.com/llvm/llvm-project/commit/752fea7c27b66b7d34925335541f843eb46f16d6
DIFF: https://github.com/llvm/llvm-project/commit/752fea7c27b66b7d34925335541f843eb46f16d6.diff
LOG: [SCCP] Add range metadata to call sites with known return ranges.
If we inferred a range for the function return value, we can add !range
at all call-sites of the function, if the range does not include undef.
Reviewers: efriedma, davide, nikic
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D83952
Added:
Modified:
llvm/lib/Transforms/Scalar/SCCP.cpp
llvm/test/Transforms/SCCP/ip-add-range-to-call.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Scalar/SCCP.cpp b/llvm/lib/Transforms/Scalar/SCCP.cpp
index 11ac7d7e1584..32dc14e5ec19 100644
--- a/llvm/lib/Transforms/Scalar/SCCP.cpp
+++ b/llvm/lib/Transforms/Scalar/SCCP.cpp
@@ -33,6 +33,7 @@
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/ValueLattice.h"
#include "llvm/Analysis/ValueLatticeUtils.h"
+#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Constants.h"
@@ -2021,9 +2022,47 @@ bool llvm::runIPSCCP(
for (const auto &I : Solver.getTrackedRetVals()) {
Function *F = I.first;
- if (isOverdefined(I.second) || F->getReturnType()->isVoidTy())
+ const ValueLatticeElement &ReturnValue = I.second;
+
+ // If there is a known constant range for the return value, add !range
+ // metadata to the function's call sites.
+ if (ReturnValue.isConstantRange() &&
+ !ReturnValue.getConstantRange().isSingleElement()) {
+ // Do not add range metadata if the return value may include undef.
+ if (ReturnValue.isConstantRangeIncludingUndef())
+ continue;
+
+ auto &CR = ReturnValue.getConstantRange();
+ for (User *User : F->users()) {
+ auto *CB = dyn_cast<CallBase>(User);
+ if (!CB || CB->getCalledFunction() != F)
+ continue;
+
+ // Limit to cases where the return value is guaranteed to be neither
+ // poison nor undef. Poison will be outside any range and currently
+ // values outside of the specified range cause immediate undefined
+ // behavior.
+ if (!isGuaranteedNotToBeUndefOrPoison(CB, CB))
+ continue;
+
+ // Do not touch existing metadata for now.
+ // TODO: We should be able to take the intersection of the existing
+ // metadata and the inferred range.
+ if (CB->getMetadata(LLVMContext::MD_range))
+ continue;
+
+ LLVMContext &Context = CB->getParent()->getContext();
+ Metadata *RangeMD[] = {
+ ConstantAsMetadata::get(ConstantInt::get(Context, CR.getLower())),
+ ConstantAsMetadata::get(ConstantInt::get(Context, CR.getUpper()))};
+ CB->setMetadata(LLVMContext::MD_range, MDNode::get(Context, RangeMD));
+ }
continue;
- findReturnsToZap(*F, ReturnsToZap, Solver);
+ }
+ if (F->getReturnType()->isVoidTy())
+ continue;
+ if (isConstant(ReturnValue) || ReturnValue.isUnknownOrUndef())
+ findReturnsToZap(*F, ReturnsToZap, Solver);
}
for (auto F : Solver.getMRVFunctionsTracked()) {
diff --git a/llvm/test/Transforms/SCCP/ip-add-range-to-call.ll b/llvm/test/Transforms/SCCP/ip-add-range-to-call.ll
index 6ae234de79a0..c12e2b5af1f9 100644
--- a/llvm/test/Transforms/SCCP/ip-add-range-to-call.ll
+++ b/llvm/test/Transforms/SCCP/ip-add-range-to-call.ll
@@ -1,10 +1,9 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -ipsccp -S %s | FileCheck %s
; Test 1.
; Both arguments and return value of @callee can be tracked. The inferred range
; can be added to call sites.
-define internal i32 @callee(i32 %x) {
+define internal noundef i32 @callee(i32 %x) {
; CHECK-LABEL: @callee(
; CHECK-NEXT: ret i32 [[X:%.*]]
;
@@ -13,8 +12,8 @@ define internal i32 @callee(i32 %x) {
define i32 @caller1() {
; CHECK-LABEL: @caller1(
-; CHECK-NEXT: [[C1:%.*]] = call i32 @callee(i32 10)
-; CHECK-NEXT: [[C2:%.*]] = call i32 @callee(i32 20)
+; CHECK-NEXT: [[C1:%.*]] = call i32 @callee(i32 10), !range [[RANGE_10_21:![0-9]+]]
+; CHECK-NEXT: [[C2:%.*]] = call i32 @callee(i32 20), !range [[RANGE_10_21]]
; CHECK-NEXT: [[A:%.*]] = add i32 [[C1]], [[C2]]
; CHECK-NEXT: ret i32 [[A]]
;
@@ -27,7 +26,7 @@ define i32 @caller1() {
define i32 @caller2(i32 %x) {
; CHECK-LABEL: @caller2(
; CHECK-NEXT: [[X_15:%.*]] = and i32 [[X:%.*]], 15
-; CHECK-NEXT: [[C:%.*]] = call i32 @callee(i32 [[X_15]])
+; CHECK-NEXT: [[C:%.*]] = call i32 @callee(i32 [[X_15]]), !range [[RANGE_10_21]]
; CHECK-NEXT: ret i32 [[C]]
;
%x.15 = and i32 %x, 15
@@ -42,7 +41,7 @@ define i32 @caller2(i32 %x) {
declare void @use_cb1(i32 (i32)*)
-define internal i32 @callee2(i32 %x) {
+define internal noundef i32 @callee2(i32 %x) {
; CHECK-LABEL: @callee2(
; CHECK-NEXT: ret i32 [[X:%.*]]
;
@@ -52,7 +51,9 @@ define internal i32 @callee2(i32 %x) {
define void @caller_cb1() {
; CHECK-LABEL: @caller_cb1(
; CHECK-NEXT: [[C1:%.*]] = call i32 @callee2(i32 9)
+; CHECK-NOT: !range
; CHECK-NEXT: [[C2:%.*]] = call i32 @callee2(i32 10)
+; CHECK-NOT: !range
; CHECK-NEXT: call void @use_cb1(i32 (i32)* @callee2)
; CHECK-NEXT: ret void
;
@@ -69,7 +70,7 @@ define void @caller_cb1() {
declare void @use_cb2(i32 (i32)*)
-define internal i32 @callee3(i32 %x) {
+define internal noundef i32 @callee3(i32 %x) {
; CHECK-LABEL: @callee3(
; CHECK-NEXT: [[C:%.*]] = icmp eq i32 [[X:%.*]], 10
; CHECK-NEXT: [[S:%.*]] = select i1 [[C]], i32 500, i32 600
@@ -82,8 +83,8 @@ define internal i32 @callee3(i32 %x) {
define void @caller_cb2() {
; CHECK-LABEL: @caller_cb2(
-; CHECK-NEXT: [[C1:%.*]] = call i32 @callee3(i32 9)
-; CHECK-NEXT: [[C2:%.*]] = call i32 @callee3(i32 10)
+; CHECK-NEXT: [[C1:%.*]] = call i32 @callee3(i32 9), !range [[RANGE_500_601:![0-9]+]]
+; CHECK-NEXT: [[C2:%.*]] = call i32 @callee3(i32 10), !range [[RANGE_500_601]]
; CHECK-NEXT: call void @use_cb2(i32 (i32)* @callee3)
; CHECK-NEXT: ret void
;
@@ -99,7 +100,7 @@ define void @caller_cb2() {
declare void @use_cb3(i32 (i32, i32)*)
-define internal i32 @callee4(i32 %x, i32 %y) {
+define internal noundef i32 @callee4(i32 %x, i32 %y) {
; CHECK-LABEL: @callee4(
; CHECK-NEXT: [[C:%.*]] = icmp eq i32 [[X:%.*]], 10
; CHECK-NEXT: [[S:%.*]] = select i1 [[C]], i32 500, i32 [[Y:%.*]]
@@ -113,7 +114,9 @@ define internal i32 @callee4(i32 %x, i32 %y) {
define void @caller_cb3() {
; CHECK-LABEL: @caller_cb3(
; CHECK-NEXT: [[C1:%.*]] = call i32 @callee4(i32 11, i32 30)
+; CHECK-NOT: !range
; CHECK-NEXT: [[C2:%.*]] = call i32 @callee4(i32 12, i32 40)
+; CHECK-NOT: !range
; CHECK-NEXT: call void @use_cb3(i32 (i32, i32)* @callee4)
; CHECK-NEXT: ret void
;
@@ -126,7 +129,7 @@ define void @caller_cb3() {
; Test 5.
; Range for the return value of callee5 includes undef. No range metadata
; should be added at call sites.
-define internal i32 @callee5(i32 %x, i32 %y) {
+define internal noundef i32 @callee5(i32 %x, i32 %y) {
; CHECK-LABEL: @callee5(
; CHECK-NEXT: [[C:%.*]] = icmp slt i32 [[X:%.*]], 15
; CHECK-NEXT: br i1 [[C]], label [[BB1:%.*]], label [[BB2:%.*]]
@@ -155,7 +158,9 @@ exit:
define i32 @caller5() {
; CHECK-LABEL: @caller5(
; CHECK-NEXT: [[C1:%.*]] = call i32 @callee5(i32 10, i32 100)
+; CHECK-NOT: !range
; CHECK-NEXT: [[C2:%.*]] = call i32 @callee5(i32 20, i32 200)
+; CHECK-NOT: !range
; CHECK-NEXT: [[A:%.*]] = add i32 [[C1]], [[C2]]
; CHECK-NEXT: ret i32 [[A]]
;
@@ -164,3 +169,6 @@ define i32 @caller5() {
%a = add i32 %c1, %c2
ret i32 %a
}
+
+; CHECK: [[RANGE_10_21]] = !{i32 0, i32 21}
+; CHECK: [[RANGE_500_601]] = !{i32 500, i32 601}
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