[llvm] 67bf9a6 - [SVEV] Recognise hardware-loop intrinsic loop.decrement.reg
Sjoerd Meijer via llvm-commits
llvm-commits at lists.llvm.org
Fri Jan 10 01:36:08 PST 2020
Author: Sjoerd Meijer
Date: 2020-01-10T09:35:00Z
New Revision: 67bf9a6154d4b82c6c01aad01141bf08c1bbd0f6
URL: https://github.com/llvm/llvm-project/commit/67bf9a6154d4b82c6c01aad01141bf08c1bbd0f6
DIFF: https://github.com/llvm/llvm-project/commit/67bf9a6154d4b82c6c01aad01141bf08c1bbd0f6.diff
LOG: [SVEV] Recognise hardware-loop intrinsic loop.decrement.reg
Teach SCEV about the @loop.decrement.reg intrinsic, which has exactly the same
semantics as a sub expression. This allows us to query hardware-loops, which
contain this @loop.decrement.reg intrinsic, so that we can calculate iteration
counts, exit values, etc. of hardwareloops.
This "int_loop_decrement_reg" intrinsic is defined as "IntrNoDuplicate". Thus,
while hardware-loops and tripcounts now become analysable by SCEV, this
prevents the usual loop transformations from applying transformations on
hardware-loops, which is what we want at this point, for which I have added
test cases for loopunrolling and IndVarSimplify and LFTR.
Differential Revision: https://reviews.llvm.org/D71563
Added:
llvm/test/Transforms/LoopUnroll/ARM/dont-unroll-loopdec.ll
Modified:
llvm/lib/Analysis/ScalarEvolution.cpp
llvm/test/Transforms/IndVarSimplify/lftr.ll
llvm/unittests/Analysis/ScalarEvolutionTest.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index e636854ad6d9..7d5c71eafed6 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -4507,6 +4507,17 @@ static Optional<BinaryOp> MatchBinaryOp(Value *V, DominatorTree &DT) {
if (!Op)
return None;
+ // Recognise intrinsic loop.decrement.reg, and as this has exactly the same
+ // semantics as a Sub, return a binary sub expression.
+ if (auto *II = dyn_cast<IntrinsicInst>(V)) {
+ switch (II->getIntrinsicID()) {
+ case Intrinsic::loop_decrement_reg:
+ return BinaryOp(Instruction::Sub, II->getOperand(0), II->getOperand(1));
+ default:
+ return None;
+ }
+ }
+
// Implementation detail: all the cleverness here should happen without
// creating new SCEV expressions -- our caller knowns tricks to avoid creating
// SCEV expressions when possible, and we should not break that.
diff --git a/llvm/test/Transforms/IndVarSimplify/lftr.ll b/llvm/test/Transforms/IndVarSimplify/lftr.ll
index 098f98d53813..abeeb5b05af5 100644
--- a/llvm/test/Transforms/IndVarSimplify/lftr.ll
+++ b/llvm/test/Transforms/IndVarSimplify/lftr.ll
@@ -153,6 +153,34 @@ loopexit:
ret i32 %i
}
+define i32 @quadratic_sgt_loopdec() {
+; CHECK-LABEL: @quadratic_sgt_loopdec(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[I:%.*]] = phi i32 [ 10, [[ENTRY:%.*]] ], [ [[I_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[I_NEXT]] = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 [[I]], i32 1)
+; CHECK-NEXT: store i32 [[I]], i32* @A
+; CHECK-NEXT: [[I2:%.*]] = mul i32 [[I]], [[I]]
+; CHECK-NEXT: [[EXITCOND:%.*]] = icmp sgt i32 [[I2]], 0
+; CHECK-NEXT: br i1 [[EXITCOND]], label [[LOOP]], label [[LOOPEXIT:%.*]]
+; CHECK: loopexit:
+; CHECK-NEXT: ret i32 0
+
+entry:
+ br label %loop
+
+loop:
+ %i = phi i32 [ 10, %entry ], [ %i.next, %loop ]
+ %i.next = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 %i, i32 1)
+ store i32 %i, i32* @A
+ %i2 = mul i32 %i, %i
+ %c = icmp sgt i32 %i2, 0
+ br i1 %c, label %loop, label %loopexit
+
+loopexit:
+ ret i32 %i
+}
@data = common global [240 x i8] zeroinitializer, align 16
@@ -629,4 +657,5 @@ exit:
}
+declare i32 @llvm.loop.decrement.reg.i32.i32.i32(i32, i32)
diff --git a/llvm/test/Transforms/LoopUnroll/ARM/dont-unroll-loopdec.ll b/llvm/test/Transforms/LoopUnroll/ARM/dont-unroll-loopdec.ll
new file mode 100644
index 000000000000..f183c67fee82
--- /dev/null
+++ b/llvm/test/Transforms/LoopUnroll/ARM/dont-unroll-loopdec.ll
@@ -0,0 +1,40 @@
+; RUN: opt -mtriple=thumbv8.1m.main -mattr=+mve.fp -loop-unroll --loop-unroll -S < %s | FileCheck %s
+
+; CHECK-LABEL: foo
+; CHECK: 5:
+; CHECK: 6: ; preds = %6, %5
+; CHECK: 15: ; preds = %6
+; CHECK: br label %16
+; CHECK: 16: ; preds = %15, %3
+; CHECK: ret void
+; CHECK: }
+
+define void @foo(i8* nocapture, i8* nocapture readonly, i32) {
+ %4 = icmp sgt i32 %2, 0
+ br i1 %4, label %5, label %16
+
+; <label>:5:
+ br label %6
+
+; <label>:6:
+ %7 = phi i32 [ %13, %6 ], [ %2, %5 ]
+ %8 = phi i8* [ %10, %6 ], [ %1, %5 ]
+ %9 = phi i8* [ %12, %6 ], [ %0, %5 ]
+ %10 = getelementptr inbounds i8, i8* %8, i32 1
+ %11 = load i8, i8* %8, align 1
+ %12 = getelementptr inbounds i8, i8* %9, i32 1
+ store i8 %11, i8* %9, align 1
+
+ %13 = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 %7, i32 1)
+
+ %14 = icmp sgt i32 %7, 1
+ br i1 %14, label %6, label %15
+
+; <label>:15:
+ br label %16
+
+; <label>:16:
+ ret void
+}
+
+declare i32 @llvm.loop.decrement.reg.i32.i32.i32(i32, i32)
diff --git a/llvm/unittests/Analysis/ScalarEvolutionTest.cpp b/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
index c42ebf656dd4..e147502ae543 100644
--- a/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
+++ b/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
@@ -1683,6 +1683,34 @@ TEST_F(ScalarEvolutionsTest, SCEVExpanderShlNSW) {
"} ");
}
+TEST_F(ScalarEvolutionsTest, SCEVLoopDecIntrinsic) {
+ LLVMContext C;
+ SMDiagnostic Err;
+ std::unique_ptr<Module> M = parseAssemblyString(
+ "define void @foo(i32 %N) { "
+ "entry: "
+ " %cmp3 = icmp sgt i32 %N, 0 "
+ " br i1 %cmp3, label %for.body, label %for.cond.cleanup "
+ "for.cond.cleanup: "
+ " ret void "
+ "for.body: "
+ " %i.04 = phi i32 [ %inc, %for.body ], [ 100, %entry ] "
+ " %inc = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 %i.04, i32 1) "
+ " %exitcond = icmp ne i32 %inc, 0 "
+ " br i1 %exitcond, label %for.cond.cleanup, label %for.body "
+ "} "
+ "declare i32 @llvm.loop.decrement.reg.i32.i32.i32(i32, i32) ",
+ Err, C);
+
+ ASSERT_TRUE(M && "Could not parse module?");
+ ASSERT_TRUE(!verifyModule(*M) && "Must have been well formed!");
+
+ runWithSE(*M, "foo", [&](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
+ auto *ScevInc = SE.getSCEV(getInstructionByName(F, "inc"));
+ EXPECT_TRUE(isa<SCEVAddRecExpr>(ScevInc));
+ });
+}
+
TEST_F(ScalarEvolutionsTest, SCEVComputeConstantDifference) {
LLVMContext C;
SMDiagnostic Err;
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