[clang] [Clang][RISCV] Add assumptions to vsetvli/vsetvlimax (PR #79975)
wangpc-pp wrote: > Can we implement this in `computeKnownBitsFromOperator/getRangeForIntrinsic`? > > https://github.com/llvm/llvm-project/blob/b21e3282864c9f7ad656c64bc375f5869ef76d19/llvm/lib/Analysis/ValueTracking.cpp#L1578-L1584 Thanks! We can implement this partly (will create another PR to do this) as we can't represent some assumptions related to runtime value `avl` like `vlhttps://github.com/llvm/llvm-project/pull/79975 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [Clang][RISCV] Add assumptions to vsetvli/vsetvlimax (PR #79975)
dtcxzyw wrote: Can we implement this in `computeKnownBitsFromOperator/getRangeForIntrinsic`? https://github.com/llvm/llvm-project/blob/b21e3282864c9f7ad656c64bc375f5869ef76d19/llvm/lib/Analysis/ValueTracking.cpp#L1578-L1584 https://github.com/llvm/llvm-project/pull/79975 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [Clang][RISCV] Add assumptions to vsetvli/vsetvlimax (PR #79975)
wangpc-pp wrote: Ping for comments. https://github.com/llvm/llvm-project/pull/79975 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [Clang][RISCV] Add assumptions to vsetvli/vsetvlimax (PR #79975)
wangpc-pp wrote: > Also I guess most of RVV intrinsic could add `const` too, that could help > some generic optimization work better like CSE. This PR doesn't add the `const` attribute, I don't know if adding `const` may help to optimize. https://github.com/llvm/llvm-project/pull/79975 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [Clang][RISCV] Add assumptions to vsetvli/vsetvlimax (PR #79975)
kito-cheng wrote: Also I guess most of RVV intrinsic could add `const` too, that could help some generic optimization work better like CSE. https://github.com/llvm/llvm-project/pull/79975 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [Clang][RISCV] Add assumptions to vsetvli/vsetvlimax (PR #79975)
kito-cheng wrote: I guess we need add that at RVVEmitter::createbuilt...@riscvvemitter.cpp? [1] https://github.com/llvm/llvm-project/blob/main/clang/utils/TableGen/RISCVVEmitter.cpp#L418 [2] https://github.com/llvm/llvm-project/blob/main/clang/include/clang/Basic/Builtins.h#L122-L124 [3] https://github.com/llvm/llvm-project/blob/main/clang/include/clang/Basic/BuiltinsARM.def#L32 https://github.com/llvm/llvm-project/pull/79975 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [Clang][RISCV] Add assumptions to vsetvli/vsetvlimax (PR #79975)
wangpc-pp wrote: > I'm concerned that llvm.assume is handled differently than a branch to > unreachable in the middle end. Actually the CodeGen part is written by referring to the LLVM IR generated by unreachable way (https://godbolt.org/z/vf1v7f744). > Have you tested that these assumes have the intended effect? Yes, the end-to-end tests show that we can generate the same assemblies. I will add a test later. https://github.com/llvm/llvm-project/pull/79975 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [Clang][RISCV] Add assumptions to vsetvli/vsetvlimax (PR #79975)
topperc wrote: I'm concerned that llvm.assume is handled differently than a branch to unreachable in the middle end. Have you tested that these assumes have the intended effect? https://github.com/llvm/llvm-project/pull/79975 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [Clang][RISCV] Add assumptions to vsetvli/vsetvlimax (PR #79975)
wangpc-pp wrote: After some random thinking, I think these assumptions may need to be added to vsetvli/vsetvlimax LLVM intrinsics instead of adding them in Clang CodeGen. In this way, we can make other frontends like `flang/Rust/TVM/MLIR/...` benefit from these assumptions. Is it possible? I don't see a way to add similar attributes to intrinsics. https://github.com/llvm/llvm-project/pull/79975 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [Clang][RISCV] Add assumptions to vsetvli/vsetvlimax (PR #79975)
hiraditya wrote: cc: @alexey-bataev @nikolaypanchenko https://github.com/llvm/llvm-project/pull/79975 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [Clang][RISCV] Add assumptions to vsetvli/vsetvlimax (PR #79975)
kito-cheng wrote: Does it possible to add testcases to demonstrate that can improve optimization? https://github.com/llvm/llvm-project/pull/79975 ___ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
[clang] [Clang][RISCV] Add assumptions to vsetvli/vsetvlimax (PR #79975)
llvmbot wrote:
@llvm/pr-subscribers-backend-risc-v
@llvm/pr-subscribers-clang
Author: Wang Pengcheng (wangpc-pp)
Changes
There are some assumptions of the return value of vsetvli/vsetvlimax,
we add them via `llvm.assume` so that middle-end optimizations can
benefit from them.
---
Patch is 141.83 KiB, truncated to 20.00 KiB below, full version:
https://github.com/llvm/llvm-project/pull/79975.diff
6 Files Affected:
- (modified) clang/include/clang/Basic/riscv_vector.td (+97-3)
- (modified)
clang/test/CodeGen/RISCV/rvv-intrinsics-autogenerated/non-policy/non-overloaded/vsetvl.c
(+575-44)
- (modified)
clang/test/CodeGen/RISCV/rvv-intrinsics-autogenerated/non-policy/non-overloaded/vsetvlmax.c
(+268-44)
- (modified)
clang/test/CodeGen/RISCV/rvv-intrinsics-autogenerated/policy/non-overloaded/vsetvl.c
(+575-44)
- (modified)
clang/test/CodeGen/RISCV/rvv-intrinsics-autogenerated/policy/non-overloaded/vsetvlmax.c
(+268-44)
- (modified) clang/test/CodeGen/RISCV/rvv-intrinsics-handcrafted/rvv-error.c
(+8-2)
``diff
diff --git a/clang/include/clang/Basic/riscv_vector.td
b/clang/include/clang/Basic/riscv_vector.td
index a00ca353588ed..84f61e3be4cfa 100644
--- a/clang/include/clang/Basic/riscv_vector.td
+++ b/clang/include/clang/Basic/riscv_vector.td
@@ -669,10 +669,104 @@ let HasBuiltinAlias = false,
HasVL = false,
HasMasked = false,
MaskedPolicyScheme = NonePolicy,
-Log2LMUL = [0],
-ManualCodegen = [{IntrinsicTypes = {ResultType};}] in // Set XLEN type
-{
+Log2LMUL = [0] in {
+
+ let ManualCodegen = [{
+{
+ // Set XLEN type
+ IntrinsicTypes = {ResultType};
+ llvm::Function *F = CGM.getIntrinsic(ID, IntrinsicTypes);
+ llvm::Value *VSetVL = Builder.CreateCall(F, Ops, "vl");
+
+ const TargetInfo = getContext().getTargetInfo();
+ auto VScale = TI.getVScaleRange(getContext().getLangOpts());
+
+ if (VScale && VScale->first && VScale->first == VScale->second) {
+// Assumptions:
+// Let:
+// fixed_vl = __riscv_v_fixed_vlen / 8;
+// We have:
+// (avl > fixed_vl || vl == avl)
+// and
+// (avl < fixed_vl * 2 || vl == fixed_vl)
+Value *FixedVL = llvm::ConstantInt::get(ResultType, VScale->first * 8);
+Value *FixedVLx2 =
+llvm::ConstantInt::get(ResultType, VScale->first * 8 * 2);
+Value *Cond0 = Builder.CreateICmpULE(
+Ops[0], ConstantInt::get(ResultType, VScale->first * 8));
+
+BasicBlock *AssumptionBlock =
+createBasicBlock("assumption", this->CurFn);
+BasicBlock *AssumptionEndBlock =
+createBasicBlock("assumption_end", this->CurFn);
+Builder.CreateCondBr(Cond0, AssumptionBlock, AssumptionEndBlock);
+
+Builder.SetInsertPoint(AssumptionBlock);
+Builder.CreateAssumption(Builder.CreateICmpEQ(VSetVL, Ops[0]));
+Builder.CreateBr(AssumptionEndBlock);
+
+Builder.SetInsertPoint(AssumptionEndBlock);
+Value *Assumption0 = Builder.CreateICmpULT(Ops[0], FixedVLx2);
+Value *Assumption1 = Builder.CreateICmpEQ(VSetVL, FixedVL);
+Builder.CreateAssumption(Builder.CreateSelect(
+Assumption0, ConstantInt::getTrue(getLLVMContext()), Assumption1));
+ } else {
+// Assumptions:
+// Let:
+// min_vl = __riscv_v_min_vlen / 8
+// We have:
+// (avl > min_vl || vl == avl)
+Value *Cond0 = Builder.CreateICmpULE(
+Ops[0], ConstantInt::get(ResultType, VScale->first * 8));
+
+BasicBlock *AssumptionBlock = createBasicBlock("assumption",
this->CurFn);
+BasicBlock *AssumptionEndBlock = createBasicBlock("assumption_end",
this->CurFn);
+Builder.CreateCondBr(Cond0, AssumptionBlock, AssumptionEndBlock);
+
+Builder.SetInsertPoint(AssumptionBlock);
+Value *Assumption = Builder.CreateICmpEQ(VSetVL, Ops[0]);
+Builder.CreateAssumption(Assumption);
+Builder.CreateBr(AssumptionEndBlock);
+
+Builder.SetInsertPoint(AssumptionEndBlock);
+ }
+ return VSetVL;
+}
+}] in
def vsetvli : RVVBuiltin<"", "zzKzKz", "i">;
+
+ let ManualCodegen = [{
+{
+ // Set XLEN type
+ IntrinsicTypes = {ResultType};
+ llvm::Function *F = CGM.getIntrinsic(ID, IntrinsicTypes);
+ llvm::Value *VSetVL = Builder.CreateCall(F, Ops, "vl");
+
+ const TargetInfo = getContext().getTargetInfo();
+ auto VScale = TI.getVScaleRange(getContext().getLangOpts());
+
+ Value *Assumption;
+ if (VScale && VScale->first && VScale->first == VScale->second)
+// Assumptions:
+// Let:
+// fixed_vl = __riscv_v_fixed_vlen / 8;
+// We have:
+// vlmax == fixed_vl
+Assumption = Builder.CreateICmpEQ(
+VSetVL, llvm::ConstantInt::get(ResultType, VScale->first * 8));
+ else
+// Assumptions:
+// Let:
