[llvm] r219876 - Preserve non-byval pointer alignment attributes using @llvm.assume when inlining
Hal Finkel
hfinkel at anl.gov
Wed Oct 15 16:44:41 PDT 2014
Author: hfinkel
Date: Wed Oct 15 18:44:41 2014
New Revision: 219876
URL: http://llvm.org/viewvc/llvm-project?rev=219876&view=rev
Log:
Preserve non-byval pointer alignment attributes using @llvm.assume when inlining
For pointer-typed function arguments, enhanced alignment can be asserted using
the 'align' attribute. When inlining, if this enhanced alignment information is
not otherwise available, preserve it using @llvm.assume-based alignment
assumptions.
Added:
llvm/trunk/test/Transforms/Inline/align.ll
Modified:
llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp
Modified: llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp?rev=219876&r1=219875&r2=219876&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp Wed Oct 15 18:44:41 2014
@@ -47,6 +47,11 @@ EnableNoAliasConversion("enable-noalias-
cl::Hidden,
cl::desc("Convert noalias attributes to metadata during inlining."));
+static cl::opt<bool>
+PreserveAlignmentAssumptions("preserve-alignment-assumptions-during-inlining",
+ cl::init(true), cl::Hidden,
+ cl::desc("Convert align attributes to assumptions during inlining."));
+
bool llvm::InlineFunction(CallInst *CI, InlineFunctionInfo &IFI,
bool InsertLifetime) {
return InlineFunction(CallSite(CI), IFI, InsertLifetime);
@@ -616,6 +621,41 @@ static void AddAliasScopeMetadata(CallSi
}
}
+/// If the inlined function has non-byval align arguments, then
+/// add @llvm.assume-based alignment assumptions to preserve this information.
+static void AddAlignmentAssumptions(CallSite CS, InlineFunctionInfo &IFI) {
+ if (!PreserveAlignmentAssumptions || !IFI.DL)
+ return;
+
+ // To avoid inserting redundant assumptions, we should check for assumptions
+ // already in the caller. To do this, we might need a DT of the caller.
+ DominatorTree DT;
+ bool DTCalculated = false;
+
+ const Function *CalledFunc = CS.getCalledFunction();
+ for (Function::const_arg_iterator I = CalledFunc->arg_begin(),
+ E = CalledFunc->arg_end(); I != E; ++I) {
+ unsigned Align = I->getType()->isPointerTy() ? I->getParamAlignment() : 0;
+ if (Align && !I->hasByValOrInAllocaAttr() && !I->hasNUses(0)) {
+ if (!DTCalculated) {
+ DT.recalculate(const_cast<Function&>(*CS.getInstruction()->getParent()
+ ->getParent()));
+ DTCalculated = true;
+ }
+
+ // If we can already prove the asserted alignment in the context of the
+ // caller, then don't bother inserting the assumption.
+ Value *Arg = CS.getArgument(I->getArgNo());
+ if (getKnownAlignment(Arg, IFI.DL, IFI.AT, CS.getInstruction(),
+ &DT) >= Align)
+ continue;
+
+ IRBuilder<>(CS.getInstruction()).CreateAlignmentAssumption(*IFI.DL, Arg,
+ Align);
+ }
+ }
+}
+
/// UpdateCallGraphAfterInlining - Once we have cloned code over from a callee
/// into the caller, update the specified callgraph to reflect the changes we
/// made. Note that it's possible that not all code was copied over, so only
@@ -943,6 +983,11 @@ bool llvm::InlineFunction(CallSite CS, I
VMap[I] = ActualArg;
}
+ // Add alignment assumptions if necessary. We do this before the inlined
+ // instructions are actually cloned into the caller so that we can easily
+ // check what will be known at the start of the inlined code.
+ AddAlignmentAssumptions(CS, IFI);
+
// We want the inliner to prune the code as it copies. We would LOVE to
// have no dead or constant instructions leftover after inlining occurs
// (which can happen, e.g., because an argument was constant), but we'll be
Added: llvm/trunk/test/Transforms/Inline/align.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/Inline/align.ll?rev=219876&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/Inline/align.ll (added)
+++ llvm/trunk/test/Transforms/Inline/align.ll Wed Oct 15 18:44:41 2014
@@ -0,0 +1,98 @@
+; RUN: opt -inline -preserve-alignment-assumptions-during-inlining -S < %s | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @hello(float* align 128 nocapture %a, float* nocapture readonly %c) #0 {
+entry:
+ %0 = load float* %c, align 4
+ %arrayidx = getelementptr inbounds float* %a, i64 5
+ store float %0, float* %arrayidx, align 4
+ ret void
+}
+
+define void @foo(float* nocapture %a, float* nocapture readonly %c) #0 {
+entry:
+ tail call void @hello(float* %a, float* %c)
+ %0 = load float* %c, align 4
+ %arrayidx = getelementptr inbounds float* %a, i64 7
+ store float %0, float* %arrayidx, align 4
+ ret void
+}
+
+; CHECK: define void @foo(float* nocapture %a, float* nocapture readonly %c) #0 {
+; CHECK: entry:
+; CHECK: %ptrint = ptrtoint float* %a to i64
+; CHECK: %maskedptr = and i64 %ptrint, 127
+; CHECK: %maskcond = icmp eq i64 %maskedptr, 0
+; CHECK: call void @llvm.assume(i1 %maskcond)
+; CHECK: %0 = load float* %c, align 4
+; CHECK: %arrayidx.i = getelementptr inbounds float* %a, i64 5
+; CHECK: store float %0, float* %arrayidx.i, align 4
+; CHECK: %1 = load float* %c, align 4
+; CHECK: %arrayidx = getelementptr inbounds float* %a, i64 7
+; CHECK: store float %1, float* %arrayidx, align 4
+; CHECK: ret void
+; CHECK: }
+
+define void @fooa(float* nocapture align 128 %a, float* nocapture readonly %c) #0 {
+entry:
+ tail call void @hello(float* %a, float* %c)
+ %0 = load float* %c, align 4
+ %arrayidx = getelementptr inbounds float* %a, i64 7
+ store float %0, float* %arrayidx, align 4
+ ret void
+}
+
+; CHECK: define void @fooa(float* nocapture align 128 %a, float* nocapture readonly %c) #0 {
+; CHECK: entry:
+; CHECK: %0 = load float* %c, align 4
+; CHECK: %arrayidx.i = getelementptr inbounds float* %a, i64 5
+; CHECK: store float %0, float* %arrayidx.i, align 4
+; CHECK: %1 = load float* %c, align 4
+; CHECK: %arrayidx = getelementptr inbounds float* %a, i64 7
+; CHECK: store float %1, float* %arrayidx, align 4
+; CHECK: ret void
+; CHECK: }
+
+define void @hello2(float* align 128 nocapture %a, float* align 128 nocapture %b, float* nocapture readonly %c) #0 {
+entry:
+ %0 = load float* %c, align 4
+ %arrayidx = getelementptr inbounds float* %a, i64 5
+ store float %0, float* %arrayidx, align 4
+ %arrayidx1 = getelementptr inbounds float* %b, i64 8
+ store float %0, float* %arrayidx1, align 4
+ ret void
+}
+
+define void @foo2(float* nocapture %a, float* nocapture %b, float* nocapture readonly %c) #0 {
+entry:
+ tail call void @hello2(float* %a, float* %b, float* %c)
+ %0 = load float* %c, align 4
+ %arrayidx = getelementptr inbounds float* %a, i64 7
+ store float %0, float* %arrayidx, align 4
+ ret void
+}
+
+; CHECK: define void @foo2(float* nocapture %a, float* nocapture %b, float* nocapture readonly %c) #0 {
+; CHECK: entry:
+; CHECK: %ptrint = ptrtoint float* %a to i64
+; CHECK: %maskedptr = and i64 %ptrint, 127
+; CHECK: %maskcond = icmp eq i64 %maskedptr, 0
+; CHECK: call void @llvm.assume(i1 %maskcond)
+; CHECK: %ptrint1 = ptrtoint float* %b to i64
+; CHECK: %maskedptr2 = and i64 %ptrint1, 127
+; CHECK: %maskcond3 = icmp eq i64 %maskedptr2, 0
+; CHECK: call void @llvm.assume(i1 %maskcond3)
+; CHECK: %0 = load float* %c, align 4
+; CHECK: %arrayidx.i = getelementptr inbounds float* %a, i64 5
+; CHECK: store float %0, float* %arrayidx.i, align 4
+; CHECK: %arrayidx1.i = getelementptr inbounds float* %b, i64 8
+; CHECK: store float %0, float* %arrayidx1.i, align 4
+; CHECK: %1 = load float* %c, align 4
+; CHECK: %arrayidx = getelementptr inbounds float* %a, i64 7
+; CHECK: store float %1, float* %arrayidx, align 4
+; CHECK: ret void
+; CHECK: }
+
+attributes #0 = { nounwind uwtable }
+
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