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[SCCP] Handle llvm.vscale intrinsic calls #114033

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Merged
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Oct 31, 2024
Merged

[SCCP] Handle llvm.vscale intrinsic calls #114033

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e99076d
[SCCP] Handle llvm.vscale intrinsic calls
hazzlim Oct 29, 2024
f809e1b
Regression test: Add branch elimination test case
hazzlim Oct 29, 2024
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6 changes: 6 additions & 0 deletions llvm/lib/Transforms/Utils/SCCPSolver.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1923,6 +1923,12 @@ void SCCPInstVisitor::handleCallResult(CallBase &CB) {
return (void)mergeInValue(IV, &CB, CopyOfVal);
}

if (II->getIntrinsicID() == Intrinsic::vscale) {
unsigned BitWidth = CB.getType()->getScalarSizeInBits();
const ConstantRange Result = getVScaleRange(II->getFunction(), BitWidth);
return (void)mergeInValue(II, ValueLatticeElement::getRange(Result));
}

if (ConstantRange::isIntrinsicSupported(II->getIntrinsicID())) {
// Compute result range for intrinsics supported by ConstantRange.
// Do this even if we don't know a range for all operands, as we may
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81 changes: 81 additions & 0 deletions llvm/test/Transforms/SCCP/vscale-intrinsic.ll
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@@ -0,0 +1,81 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt < %s -passes=sccp -S | FileCheck %s

define i1 @vscale_i32_noattr() {
; CHECK-LABEL: define i1 @vscale_i32_noattr() {
; CHECK-NEXT: [[SCALE:%.*]] = call i32 @llvm.vscale.i32()
; CHECK-NEXT: [[CMP2:%.*]] = icmp ule i32 [[SCALE]], 16
; CHECK-NEXT: [[RES:%.*]] = and i1 true, [[CMP2]]
; CHECK-NEXT: ret i1 [[RES]]
;
%scale = call i32 @llvm.vscale.i32()
%cmp1 = icmp uge i32 %scale, 1
%cmp2 = icmp ule i32 %scale, 16
%res = and i1 %cmp1, %cmp2
ret i1 %res
}

define i1 @vscale_i32_attr() vscale_range(1, 16) {
; CHECK-LABEL: define i1 @vscale_i32_attr(
; CHECK-SAME: ) #[[ATTR0:[0-9]+]] {
; CHECK-NEXT: [[SCALE:%.*]] = call i32 @llvm.vscale.i32()
; CHECK-NEXT: ret i1 true
;
%scale = call i32 @llvm.vscale.i32()
%cmp1 = icmp uge i32 %scale, 1
%cmp2 = icmp ule i32 %scale, 16
%res = and i1 %cmp1, %cmp2
ret i1 %res
}

define i1 @vscale_i64_noattr() {
; CHECK-LABEL: define i1 @vscale_i64_noattr() {
; CHECK-NEXT: [[SCALE:%.*]] = call i64 @llvm.vscale.i64()
; CHECK-NEXT: [[CMP2:%.*]] = icmp ule i64 [[SCALE]], 16
; CHECK-NEXT: [[RES:%.*]] = and i1 true, [[CMP2]]
; CHECK-NEXT: ret i1 [[RES]]
;
%scale = call i64 @llvm.vscale.i64()
%cmp1 = icmp uge i64 %scale, 1
%cmp2 = icmp ule i64 %scale, 16
%res = and i1 %cmp1, %cmp2
ret i1 %res
}

define i1 @vscale_i64_attr() vscale_range(1, 16) {
; CHECK-LABEL: define i1 @vscale_i64_attr(
; CHECK-SAME: ) #[[ATTR0]] {
; CHECK-NEXT: [[SCALE:%.*]] = call i64 @llvm.vscale.i64()
; CHECK-NEXT: ret i1 true
;
%scale = call i64 @llvm.vscale.i64()
%cmp1 = icmp uge i64 %scale, 1
%cmp2 = icmp ule i64 %scale, 16
%res = and i1 %cmp1, %cmp2
ret i1 %res
}

define i32 @vscale_branch_elim(i32 %x) vscale_range(1, 16) {
; CHECK-LABEL: define i32 @vscale_branch_elim(
; CHECK-SAME: i32 [[X:%.*]]) #[[ATTR0]] {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[SCALE:%.*]] = call i32 @llvm.vscale.i32()
; CHECK-NEXT: [[BOUND:%.*]] = shl nuw nsw i32 [[SCALE]], 3
; CHECK-NEXT: br label %[[IF_END:.*]]
; CHECK: [[IF_END]]:
; CHECK-NEXT: ret i32 [[X]]
;
entry:
%scale = call i32 @llvm.vscale.i32()
%bound = shl nsw nuw i32 %scale, 3
%cmp = icmp uge i32 1, %bound
br i1 %cmp, label %if.then, label %if.end

if.then:
%double = mul i32 %x, 2
br label %if.end

if.end:
%res = phi i32 [ %x, %entry ], [ %double, %if.then]
ret i32 %res
}
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