[clang] [llvm] [SCCP] Infer return attributes in SCCP as well (PR #106732)
Nikita Popov via cfe-commits
cfe-commits at lists.llvm.org
Fri Aug 30 08:15:49 PDT 2024
https://github.com/nikic updated https://github.com/llvm/llvm-project/pull/106732
>From 50efbbd59ed639d9604f3b13faf1fb8be60161e7 Mon Sep 17 00:00:00 2001
From: Nikita Popov <npopov at redhat.com>
Date: Fri, 30 Aug 2024 12:46:53 +0200
Subject: [PATCH 1/2] [SCCP] Infer return attributes in SCCP as well
We can infer the range/nonnull attributes in non-interprocedural
SCCP as well. The results may be better after the function has
been simplified.
---
.../llvm/Transforms/Utils/SCCPSolver.h | 4 ++-
llvm/lib/Transforms/IPO/SCCP.cpp | 28 ++--------------
llvm/lib/Transforms/Scalar/SCCP.cpp | 8 +++++
llvm/lib/Transforms/Utils/SCCPSolver.cpp | 32 ++++++++++++++++++-
.../icmp-ashr-breaking-select-idiom.ll | 4 +--
llvm/test/Transforms/SCCP/exact-flags.ll | 4 +--
llvm/test/Transforms/SCCP/phis.ll | 4 +--
llvm/test/Transforms/SCCP/pointer-nonnull.ll | 10 ++----
8 files changed, 54 insertions(+), 40 deletions(-)
diff --git a/llvm/include/llvm/Transforms/Utils/SCCPSolver.h b/llvm/include/llvm/Transforms/Utils/SCCPSolver.h
index 1f959311295258..61a500b82875fb 100644
--- a/llvm/include/llvm/Transforms/Utils/SCCPSolver.h
+++ b/llvm/include/llvm/Transforms/Utils/SCCPSolver.h
@@ -137,7 +137,7 @@ class SCCPSolver {
const ValueLatticeElement &getLatticeValueFor(Value *V) const;
/// getTrackedRetVals - Get the inferred return value map.
- const MapVector<Function *, ValueLatticeElement> &getTrackedRetVals();
+ const MapVector<Function *, ValueLatticeElement> &getTrackedRetVals() const;
/// getTrackedGlobals - Get and return the set of inferred initializers for
/// global variables.
@@ -190,6 +190,8 @@ class SCCPSolver {
bool removeNonFeasibleEdges(BasicBlock *BB, DomTreeUpdater &DTU,
BasicBlock *&NewUnreachableBB) const;
+ void inferReturnAttributes() const;
+
bool tryToReplaceWithConstant(Value *V);
// Helper to check if \p LV is either a constant or a constant
diff --git a/llvm/lib/Transforms/IPO/SCCP.cpp b/llvm/lib/Transforms/IPO/SCCP.cpp
index 5ef08c4a2d725d..cbf511c53d29da 100644
--- a/llvm/lib/Transforms/IPO/SCCP.cpp
+++ b/llvm/lib/Transforms/IPO/SCCP.cpp
@@ -277,34 +277,12 @@ static bool runIPSCCP(
// whether other functions are optimizable.
SmallVector<ReturnInst*, 8> ReturnsToZap;
+ Solver.inferReturnAttributes();
for (const auto &I : Solver.getTrackedRetVals()) {
Function *F = I.first;
const ValueLatticeElement &ReturnValue = I.second;
-
- // If there is a known constant range for the return value, add range
- // attribute to the return value.
- if (ReturnValue.isConstantRange() &&
- !ReturnValue.getConstantRange().isSingleElement()) {
- // Do not add range metadata if the return value may include undef.
- if (ReturnValue.isConstantRangeIncludingUndef())
- continue;
-
- // Take the intersection of the existing attribute and the inferred range.
- ConstantRange CR = ReturnValue.getConstantRange();
- if (F->hasRetAttribute(Attribute::Range))
- CR = CR.intersectWith(F->getRetAttribute(Attribute::Range).getRange());
- F->addRangeRetAttr(CR);
- continue;
- }
- // Infer nonnull return attribute.
- if (F->getReturnType()->isPointerTy() && ReturnValue.isNotConstant() &&
- ReturnValue.getNotConstant()->isNullValue() &&
- !F->hasRetAttribute(Attribute::NonNull)) {
- F->addRetAttr(Attribute::NonNull);
- continue;
- }
- if (F->getReturnType()->isVoidTy())
- continue;
+ assert(!F->getReturnType()->isVoidTy() &&
+ "should not track void functions");
if (SCCPSolver::isConstant(ReturnValue) || ReturnValue.isUnknownOrUndef())
findReturnsToZap(*F, ReturnsToZap, Solver);
}
diff --git a/llvm/lib/Transforms/Scalar/SCCP.cpp b/llvm/lib/Transforms/Scalar/SCCP.cpp
index caf9f890418e29..0330460e7df8ab 100644
--- a/llvm/lib/Transforms/Scalar/SCCP.cpp
+++ b/llvm/lib/Transforms/Scalar/SCCP.cpp
@@ -24,6 +24,7 @@
#include "llvm/Analysis/DomTreeUpdater.h"
#include "llvm/Analysis/GlobalsModRef.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/Analysis/ValueLatticeUtils.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constant.h"
@@ -66,6 +67,11 @@ static bool runSCCP(Function &F, const DataLayout &DL,
DL, [TLI](Function &F) -> const TargetLibraryInfo & { return *TLI; },
F.getContext());
+ // While we don't do any actual inter-procedural analysis, still track
+ // return values so we can infer attributes.
+ if (canTrackReturnsInterprocedurally(&F))
+ Solver.addTrackedFunction(&F);
+
// Mark the first block of the function as being executable.
Solver.markBlockExecutable(&F.front());
@@ -115,6 +121,8 @@ static bool runSCCP(Function &F, const DataLayout &DL,
if (!DeadBB->hasAddressTaken())
DTU.deleteBB(DeadBB);
+ Solver.inferReturnAttributes();
+
return MadeChanges;
}
diff --git a/llvm/lib/Transforms/Utils/SCCPSolver.cpp b/llvm/lib/Transforms/Utils/SCCPSolver.cpp
index 59775d2199ca61..5cb0fc3ec5d633 100644
--- a/llvm/lib/Transforms/Utils/SCCPSolver.cpp
+++ b/llvm/lib/Transforms/Utils/SCCPSolver.cpp
@@ -354,6 +354,36 @@ bool SCCPSolver::removeNonFeasibleEdges(BasicBlock *BB, DomTreeUpdater &DTU,
return true;
}
+void SCCPSolver::inferReturnAttributes() const {
+ for (const auto &I : getTrackedRetVals()) {
+ Function *F = I.first;
+ const ValueLatticeElement &ReturnValue = I.second;
+
+ // If there is a known constant range for the return value, add range
+ // attribute to the return value.
+ if (ReturnValue.isConstantRange() &&
+ !ReturnValue.getConstantRange().isSingleElement()) {
+ // Do not add range metadata if the return value may include undef.
+ if (ReturnValue.isConstantRangeIncludingUndef())
+ continue;
+
+ // Take the intersection of the existing attribute and the inferred range.
+ ConstantRange CR = ReturnValue.getConstantRange();
+ if (F->hasRetAttribute(Attribute::Range))
+ CR = CR.intersectWith(F->getRetAttribute(Attribute::Range).getRange());
+ F->addRangeRetAttr(CR);
+ continue;
+ }
+ // Infer nonnull return attribute.
+ if (F->getReturnType()->isPointerTy() && ReturnValue.isNotConstant() &&
+ ReturnValue.getNotConstant()->isNullValue() &&
+ !F->hasRetAttribute(Attribute::NonNull)) {
+ F->addRetAttr(Attribute::NonNull);
+ continue;
+ }
+ }
+}
+
/// Helper class for SCCPSolver. This implements the instruction visitor and
/// holds all the state.
class SCCPInstVisitor : public InstVisitor<SCCPInstVisitor> {
@@ -2168,7 +2198,7 @@ const ValueLatticeElement &SCCPSolver::getLatticeValueFor(Value *V) const {
}
const MapVector<Function *, ValueLatticeElement> &
-SCCPSolver::getTrackedRetVals() {
+SCCPSolver::getTrackedRetVals() const {
return Visitor->getTrackedRetVals();
}
diff --git a/llvm/test/Transforms/PhaseOrdering/icmp-ashr-breaking-select-idiom.ll b/llvm/test/Transforms/PhaseOrdering/icmp-ashr-breaking-select-idiom.ll
index 35d5ceeb91950f..871615dbd62852 100644
--- a/llvm/test/Transforms/PhaseOrdering/icmp-ashr-breaking-select-idiom.ll
+++ b/llvm/test/Transforms/PhaseOrdering/icmp-ashr-breaking-select-idiom.ll
@@ -2,7 +2,7 @@
; RUN: opt -O1 -S < %s | FileCheck %s
define i32 @testa(i32 %mul) {
-; CHECK-LABEL: define range(i32 -65536, 65536) i32 @testa(
+; CHECK-LABEL: define range(i32 -65536, 32768) i32 @testa(
; CHECK-SAME: i32 [[MUL:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] {
; CHECK-NEXT: [[SHR:%.*]] = ashr i32 [[MUL]], 15
; CHECK-NEXT: [[SPEC_SELECT_I:%.*]] = tail call i32 @llvm.smin.i32(i32 [[SHR]], i32 32767)
@@ -16,7 +16,7 @@ define i32 @testa(i32 %mul) {
}
define i32 @testb(i32 %mul) {
-; CHECK-LABEL: define range(i32 -16777216, 16777216) i32 @testb(
+; CHECK-LABEL: define range(i32 -128, 128) i32 @testb(
; CHECK-SAME: i32 [[MUL:%.*]]) local_unnamed_addr #[[ATTR0]] {
; CHECK-NEXT: [[SHR102:%.*]] = ashr i32 [[MUL]], 7
; CHECK-NEXT: [[TMP1:%.*]] = tail call i32 @llvm.smax.i32(i32 [[SHR102]], i32 -128)
diff --git a/llvm/test/Transforms/SCCP/exact-flags.ll b/llvm/test/Transforms/SCCP/exact-flags.ll
index a5e3bf111bbd9d..f860ddb6fe9cfb 100644
--- a/llvm/test/Transforms/SCCP/exact-flags.ll
+++ b/llvm/test/Transforms/SCCP/exact-flags.ll
@@ -2,7 +2,7 @@
; RUN: opt -passes=sccp < %s -S | FileCheck %s
define i8 @ashr_to_lshr(i8 %x, i8 %y) {
-; CHECK-LABEL: define i8 @ashr_to_lshr(
+; CHECK-LABEL: define range(i8 0, -128) i8 @ashr_to_lshr(
; CHECK-SAME: i8 [[X:%.*]], i8 [[Y:%.*]]) {
; CHECK-NEXT: [[P:%.*]] = and i8 [[X]], 127
; CHECK-NEXT: [[R:%.*]] = lshr exact i8 [[P]], [[Y]]
@@ -14,7 +14,7 @@ define i8 @ashr_to_lshr(i8 %x, i8 %y) {
}
define i8 @sdiv_to_udiv(i8 %x, i8 %y) {
-; CHECK-LABEL: define i8 @sdiv_to_udiv(
+; CHECK-LABEL: define range(i8 0, -128) i8 @sdiv_to_udiv(
; CHECK-SAME: i8 [[X:%.*]], i8 [[Y:%.*]]) {
; CHECK-NEXT: [[X1:%.*]] = and i8 [[X]], 127
; CHECK-NEXT: [[Y1:%.*]] = and i8 [[Y]], 127
diff --git a/llvm/test/Transforms/SCCP/phis.ll b/llvm/test/Transforms/SCCP/phis.ll
index 9264a6eaefb85d..dae843ca955955 100644
--- a/llvm/test/Transforms/SCCP/phis.ll
+++ b/llvm/test/Transforms/SCCP/phis.ll
@@ -100,7 +100,7 @@ end:
}
define <2 x i16> @phi_vector_merge1(i1 %c, <2 x i8> %a) {
-; CHECK-LABEL: define <2 x i16> @phi_vector_merge1(
+; CHECK-LABEL: define range(i16 2, 259) <2 x i16> @phi_vector_merge1(
; CHECK-SAME: i1 [[C:%.*]], <2 x i8> [[A:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*]]:
; CHECK-NEXT: [[ZEXT:%.*]] = zext <2 x i8> [[A]] to <2 x i16>
@@ -126,7 +126,7 @@ join:
}
define <2 x i16> @phi_vector_merge2(i1 %c, <2 x i8> %a) {
-; CHECK-LABEL: define <2 x i16> @phi_vector_merge2(
+; CHECK-LABEL: define range(i16 2, 259) <2 x i16> @phi_vector_merge2(
; CHECK-SAME: i1 [[C:%.*]], <2 x i8> [[A:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*]]:
; CHECK-NEXT: [[ZEXT:%.*]] = zext <2 x i8> [[A]] to <2 x i16>
diff --git a/llvm/test/Transforms/SCCP/pointer-nonnull.ll b/llvm/test/Transforms/SCCP/pointer-nonnull.ll
index 08d4a76345bb63..c3a6a762e31744 100644
--- a/llvm/test/Transforms/SCCP/pointer-nonnull.ll
+++ b/llvm/test/Transforms/SCCP/pointer-nonnull.ll
@@ -232,13 +232,9 @@ define i1 @ip_test_nonnull_caller(ptr %p) {
}
define ptr @ret_nonnull_pointer(ptr nonnull %p) {
-; SCCP-LABEL: define ptr @ret_nonnull_pointer(
-; SCCP-SAME: ptr nonnull [[P:%.*]]) {
-; SCCP-NEXT: ret ptr [[P]]
-;
-; IPSCCP-LABEL: define nonnull ptr @ret_nonnull_pointer(
-; IPSCCP-SAME: ptr nonnull [[P:%.*]]) {
-; IPSCCP-NEXT: ret ptr [[P]]
+; CHECK-LABEL: define nonnull ptr @ret_nonnull_pointer(
+; CHECK-SAME: ptr nonnull [[P:%.*]]) {
+; CHECK-NEXT: ret ptr [[P]]
;
ret ptr %p
}
>From 9eaece6cbfd90618ab2683fa5f2d0ade2c03258c Mon Sep 17 00:00:00 2001
From: Nikita Popov <npopov at redhat.com>
Date: Fri, 30 Aug 2024 17:15:32 +0200
Subject: [PATCH 2/2] Update clang test
---
clang/test/CodeGen/attr-counted-by.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/clang/test/CodeGen/attr-counted-by.c b/clang/test/CodeGen/attr-counted-by.c
index 3ed8b6f0c71861..ab36b6e7720ba3 100644
--- a/clang/test/CodeGen/attr-counted-by.c
+++ b/clang/test/CodeGen/attr-counted-by.c
@@ -639,7 +639,7 @@ void test6(struct anon_struct *p, int index) {
p->array[index] = __builtin_dynamic_object_size(p->array, 1);
}
-// SANITIZE-WITH-ATTR-LABEL: define dso_local i64 @test6_bdos(
+// SANITIZE-WITH-ATTR-LABEL: define dso_local range(i64 0, -3) i64 @test6_bdos(
// SANITIZE-WITH-ATTR-SAME: ptr nocapture noundef readonly [[P:%.*]]) local_unnamed_addr #[[ATTR2]] {
// SANITIZE-WITH-ATTR-NEXT: entry:
// SANITIZE-WITH-ATTR-NEXT: [[DOT_COUNTED_BY_GEP:%.*]] = getelementptr inbounds i8, ptr [[P]], i64 8
@@ -649,7 +649,7 @@ void test6(struct anon_struct *p, int index) {
// SANITIZE-WITH-ATTR-NEXT: [[TMP1:%.*]] = select i1 [[DOTINV]], i64 0, i64 [[TMP0]]
// SANITIZE-WITH-ATTR-NEXT: ret i64 [[TMP1]]
//
-// NO-SANITIZE-WITH-ATTR-LABEL: define dso_local i64 @test6_bdos(
+// NO-SANITIZE-WITH-ATTR-LABEL: define dso_local range(i64 0, -3) i64 @test6_bdos(
// NO-SANITIZE-WITH-ATTR-SAME: ptr nocapture noundef readonly [[P:%.*]]) local_unnamed_addr #[[ATTR2]] {
// NO-SANITIZE-WITH-ATTR-NEXT: entry:
// NO-SANITIZE-WITH-ATTR-NEXT: [[DOT_COUNTED_BY_GEP:%.*]] = getelementptr inbounds i8, ptr [[P]], i64 8
@@ -955,7 +955,7 @@ void test10(struct union_of_fams *p, int index) {
p->bytes[index] = (unsigned char)__builtin_dynamic_object_size(p->bytes, 1);
}
-// SANITIZE-WITH-ATTR-LABEL: define dso_local range(i64 -2147483648, 2147483648) i64 @test10_bdos(
+// SANITIZE-WITH-ATTR-LABEL: define dso_local range(i64 0, 2147483648) i64 @test10_bdos(
// SANITIZE-WITH-ATTR-SAME: ptr nocapture noundef readonly [[P:%.*]]) local_unnamed_addr #[[ATTR2]] {
// SANITIZE-WITH-ATTR-NEXT: entry:
// SANITIZE-WITH-ATTR-NEXT: [[DOT_COUNTED_BY_GEP:%.*]] = getelementptr inbounds i8, ptr [[P]], i64 8
@@ -964,7 +964,7 @@ void test10(struct union_of_fams *p, int index) {
// SANITIZE-WITH-ATTR-NEXT: [[TMP0:%.*]] = zext nneg i32 [[NARROW]] to i64
// SANITIZE-WITH-ATTR-NEXT: ret i64 [[TMP0]]
//
-// NO-SANITIZE-WITH-ATTR-LABEL: define dso_local range(i64 -2147483648, 2147483648) i64 @test10_bdos(
+// NO-SANITIZE-WITH-ATTR-LABEL: define dso_local range(i64 0, 2147483648) i64 @test10_bdos(
// NO-SANITIZE-WITH-ATTR-SAME: ptr nocapture noundef readonly [[P:%.*]]) local_unnamed_addr #[[ATTR2]] {
// NO-SANITIZE-WITH-ATTR-NEXT: entry:
// NO-SANITIZE-WITH-ATTR-NEXT: [[DOT_COUNTED_BY_GEP:%.*]] = getelementptr inbounds i8, ptr [[P]], i64 8
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