[llvm] [GVN] Teach GVN simple masked load/store forwarding (PR #157689)
Ramkumar Ramachandra via llvm-commits
llvm-commits at lists.llvm.org
Tue Sep 9 10:23:37 PDT 2025
================
@@ -36,6 +36,164 @@ define <128 x i8> @f1(ptr %a0, <128 x i8> %a1, <128 x i8> %a2) {
ret <128 x i8> %v4
}
+define <4 x float> @forward_masked_load(ptr %0, ptr %1) {
+; CHECK-LABEL: @forward_masked_load(
+; CHECK-NEXT: [[TMP4:%.*]] = call <4 x float> @llvm.masked.load.v4f32.p0(ptr [[TMP0:%.*]], i32 1, <4 x i1> splat (i1 true), <4 x float> zeroinitializer)
+; CHECK-NEXT: call void @llvm.masked.store.v4f32.p0(<4 x float> [[TMP4]], ptr [[TMP1:%.*]], i32 1, <4 x i1> splat (i1 true))
+; CHECK-NEXT: ret <4 x float> [[TMP4]]
+;
+ %6 = call <4 x i1> @llvm.get.active.lane.mask.v4i1.i32(i32 0, i32 4)
+ %7 = call <4 x float> @llvm.masked.load.v4f32.p0(ptr %0, i32 1, <4 x i1> %6, <4 x float> zeroinitializer)
+ call void @llvm.masked.store.v4f32.p0(<4 x float> %7, ptr %1, i32 1, <4 x i1> %6)
+ %8 = call <4 x float> @llvm.masked.load.v4f32.p0(ptr %1, i32 1, <4 x i1> %6, <4 x float> zeroinitializer)
+ ret <4 x float> %8
+}
+
+define <4 x float> @forward_binop_splat_i1_mask(ptr %0, ptr %1) {
+; CHECK-LABEL: @forward_binop_splat_i1_mask(
+; CHECK-NEXT: [[LOAD_0_0:%.*]] = call <4 x float> @llvm.masked.load.v4f32.p0(ptr [[TMP0:%.*]], i32 1, <4 x i1> splat (i1 true), <4 x float> zeroinitializer)
+; CHECK-NEXT: [[GEP_0_16:%.*]] = getelementptr i8, ptr [[TMP0]], i32 16
+; CHECK-NEXT: [[LOAD_0_16:%.*]] = call <4 x float> @llvm.masked.load.v4f32.p0(ptr [[GEP_0_16]], i32 1, <4 x i1> splat (i1 true), <4 x float> zeroinitializer)
+; CHECK-NEXT: [[FMUL:%.*]] = fmul <4 x float> [[LOAD_0_0]], [[LOAD_0_16]]
+; CHECK-NEXT: call void @llvm.masked.store.v4f32.p0(<4 x float> [[FMUL]], ptr [[TMP1:%.*]], i32 1, <4 x i1> splat (i1 true))
+; CHECK-NEXT: ret <4 x float> [[FMUL]]
+;
+ %mask = tail call <4 x i1> @llvm.get.active.lane.mask.v4i1.i32(i32 0, i32 4)
+ %load.0.0 = call <4 x float> @llvm.masked.load.v4f32.p0(ptr %0, i32 1, <4 x i1> %mask, <4 x float> zeroinitializer)
+ %gep.0.16 = getelementptr i8, ptr %0, i32 16
+ %load.0.16 = call <4 x float> @llvm.masked.load.v4f32.p0(ptr %gep.0.16, i32 1, <4 x i1> %mask, <4 x float> zeroinitializer)
+ %fmul = fmul <4 x float> %load.0.0, %load.0.16
+ call void @llvm.masked.store.v4f32.p0(<4 x float> %fmul, ptr %1, i32 1, <4 x i1> %mask)
+ %load.1.0 = call <4 x float> @llvm.masked.load.v4f32.p0(ptr %1, i32 1, <4 x i1> %mask, <4 x float> zeroinitializer)
+ ret <4 x float> %load.1.0
+}
+
+define <4 x float> @forward_binop_with_sel(ptr %0, ptr %1, i32 %a, i32 %b, <4 x float> %passthrough) {
+; CHECK-LABEL: @forward_binop_with_sel(
+; CHECK-NEXT: [[MASK:%.*]] = tail call <4 x i1> @llvm.get.active.lane.mask.v4i1.i32(i32 [[A:%.*]], i32 [[B:%.*]])
+; CHECK-NEXT: [[LOAD_0_0:%.*]] = call <4 x float> @llvm.masked.load.v4f32.p0(ptr [[TMP0:%.*]], i32 1, <4 x i1> [[MASK]], <4 x float> zeroinitializer)
+; CHECK-NEXT: [[GEP_0_16:%.*]] = getelementptr i8, ptr [[TMP0]], i32 16
+; CHECK-NEXT: [[LOAD_0_16:%.*]] = call <4 x float> @llvm.masked.load.v4f32.p0(ptr [[GEP_0_16]], i32 1, <4 x i1> [[MASK]], <4 x float> zeroinitializer)
+; CHECK-NEXT: [[FMUL:%.*]] = fmul <4 x float> [[LOAD_0_0]], [[LOAD_0_16]]
+; CHECK-NEXT: call void @llvm.masked.store.v4f32.p0(<4 x float> [[FMUL]], ptr [[TMP1:%.*]], i32 1, <4 x i1> [[MASK]])
+; CHECK-NEXT: [[TMP3:%.*]] = select <4 x i1> [[MASK]], <4 x float> [[FMUL]], <4 x float> [[PASSTHROUGH:%.*]]
+; CHECK-NEXT: ret <4 x float> [[TMP3]]
+;
+ %mask = tail call <4 x i1> @llvm.get.active.lane.mask.v4i1.i32(i32 %a, i32 %b)
+ %load.0.0 = call <4 x float> @llvm.masked.load.v4f32.p0(ptr %0, i32 1, <4 x i1> %mask, <4 x float> zeroinitializer)
+ %gep.0.16 = getelementptr i8, ptr %0, i32 16
+ %load.0.16 = call <4 x float> @llvm.masked.load.v4f32.p0(ptr %gep.0.16, i32 1, <4 x i1> %mask, <4 x float> zeroinitializer)
+ %fmul = fmul <4 x float> %load.0.0, %load.0.16
+ call void @llvm.masked.store.v4f32.p0(<4 x float> %fmul, ptr %1, i32 1, <4 x i1> %mask)
+ %load.1.0 = call <4 x float> @llvm.masked.load.v4f32.p0(ptr %1, i32 1, <4 x i1> %mask, <4 x float> %passthrough)
+ ret <4 x float> %load.1.0
+}
+
+define <vscale x 4 x float> @forward_masked_load_scalable(ptr %0, ptr %1, <vscale x 4 x float> %passthrough) {
+; CHECK-LABEL: @forward_masked_load_scalable(
+; CHECK-NEXT: [[TMP3:%.*]] = call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i32(i32 0, i32 4)
+; CHECK-NEXT: [[TMP4:%.*]] = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr [[TMP0:%.*]], i32 1, <vscale x 4 x i1> [[TMP3]], <vscale x 4 x float> [[PASSTHROUGH:%.*]])
+; CHECK-NEXT: call void @llvm.masked.store.nxv4f32.p0(<vscale x 4 x float> [[TMP4]], ptr [[TMP1:%.*]], i32 1, <vscale x 4 x i1> [[TMP3]])
+; CHECK-NEXT: ret <vscale x 4 x float> [[TMP4]]
+;
+ %6 = call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i32(i32 0, i32 4)
+ %7 = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr %0, i32 1, <vscale x 4 x i1> %6, <vscale x 4 x float> %passthrough)
+ call void @llvm.masked.store.nxv4f32.p0(<vscale x 4 x float> %7, ptr %1, i32 1, <vscale x 4 x i1> %6)
+ %8 = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr %1, i32 1, <vscale x 4 x i1> %6, <vscale x 4 x float> %passthrough)
+ ret <vscale x 4 x float> %8
+}
+
+define <vscale x 4 x float> @bail_on_different_passthrough(ptr %0, ptr %1, <vscale x 4 x float> %passthrough) {
+; CHECK-LABEL: @bail_on_different_passthrough(
+; CHECK-NEXT: [[TMP3:%.*]] = call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i32(i32 0, i32 4)
+; CHECK-NEXT: [[TMP4:%.*]] = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr [[TMP0:%.*]], i32 1, <vscale x 4 x i1> [[TMP3]], <vscale x 4 x float> zeroinitializer)
+; CHECK-NEXT: call void @llvm.masked.store.nxv4f32.p0(<vscale x 4 x float> [[TMP4]], ptr [[TMP1:%.*]], i32 1, <vscale x 4 x i1> [[TMP3]])
+; CHECK-NEXT: [[TMP5:%.*]] = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr [[TMP1]], i32 1, <vscale x 4 x i1> [[TMP3]], <vscale x 4 x float> [[PASSTHROUGH:%.*]])
+; CHECK-NEXT: ret <vscale x 4 x float> [[TMP5]]
+;
+ %6 = call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i32(i32 0, i32 4)
+ %7 = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr %0, i32 1, <vscale x 4 x i1> %6, <vscale x 4 x float> zeroinitializer)
+ call void @llvm.masked.store.nxv4f32.p0(<vscale x 4 x float> %7, ptr %1, i32 1, <vscale x 4 x i1> %6)
+ %8 = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr %1, i32 1, <vscale x 4 x i1> %6, <vscale x 4 x float> %passthrough)
+ ret <vscale x 4 x float> %8
+}
+
+define <vscale x 4 x float> @forward_binop_with_sel_scalable(ptr %0, ptr %1, <vscale x 4 x float> %passthrough) {
+; CHECK-LABEL: @forward_binop_with_sel_scalable(
+; CHECK-NEXT: [[MASK:%.*]] = tail call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i32(i32 0, i32 4)
+; CHECK-NEXT: [[LOAD_0_0:%.*]] = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr [[TMP0:%.*]], i32 1, <vscale x 4 x i1> [[MASK]], <vscale x 4 x float> zeroinitializer)
+; CHECK-NEXT: [[GEP_0_16:%.*]] = getelementptr i8, ptr [[TMP0]], i32 16
+; CHECK-NEXT: [[LOAD_0_16:%.*]] = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr [[GEP_0_16]], i32 1, <vscale x 4 x i1> [[MASK]], <vscale x 4 x float> zeroinitializer)
+; CHECK-NEXT: [[FMUL:%.*]] = fmul <vscale x 4 x float> [[LOAD_0_0]], [[LOAD_0_16]]
+; CHECK-NEXT: call void @llvm.masked.store.nxv4f32.p0(<vscale x 4 x float> [[FMUL]], ptr [[TMP1:%.*]], i32 1, <vscale x 4 x i1> [[MASK]])
+; CHECK-NEXT: [[TMP3:%.*]] = select <vscale x 4 x i1> [[MASK]], <vscale x 4 x float> [[FMUL]], <vscale x 4 x float> [[PASSTHROUGH:%.*]]
+; CHECK-NEXT: ret <vscale x 4 x float> [[TMP3]]
+;
+ %mask = tail call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i32(i32 0, i32 4)
+ %load.0.0 = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr %0, i32 1, <vscale x 4 x i1> %mask, <vscale x 4 x float> zeroinitializer)
+ %gep.0.16 = getelementptr i8, ptr %0, i32 16
+ %load.0.16 = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr %gep.0.16, i32 1, <vscale x 4 x i1> %mask, <vscale x 4 x float> zeroinitializer)
+ %fmul = fmul <vscale x 4 x float> %load.0.0, %load.0.16
+ call void @llvm.masked.store.nxv4f32.p0(<vscale x 4 x float> %fmul, ptr %1, i32 1, <vscale x 4 x i1> %mask)
+ %load.1.0 = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr %1, i32 1, <vscale x 4 x i1> %mask, <vscale x 4 x float> %passthrough)
+ ret <vscale x 4 x float> %load.1.0
+}
+
+define <vscale x 4 x float> @load_mask_differs(ptr %0, ptr %1, <vscale x 4 x float> %passthrough) {
+; CHECK-LABEL: @load_mask_differs(
+; CHECK-NEXT: [[MASK0:%.*]] = tail call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i32(i32 0, i32 8)
+; CHECK-NEXT: [[MASK1:%.*]] = tail call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i32(i32 0, i32 4)
+; CHECK-NEXT: [[LOAD_0_0:%.*]] = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr [[TMP0:%.*]], i32 1, <vscale x 4 x i1> [[MASK0]], <vscale x 4 x float> zeroinitializer)
+; CHECK-NEXT: [[GEP_0_16:%.*]] = getelementptr i8, ptr [[TMP0]], i32 16
+; CHECK-NEXT: [[LOAD_0_16:%.*]] = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr [[GEP_0_16]], i32 1, <vscale x 4 x i1> [[MASK0]], <vscale x 4 x float> zeroinitializer)
+; CHECK-NEXT: [[FMUL:%.*]] = fmul <vscale x 4 x float> [[LOAD_0_0]], [[LOAD_0_16]]
+; CHECK-NEXT: call void @llvm.masked.store.nxv4f32.p0(<vscale x 4 x float> [[FMUL]], ptr [[TMP1:%.*]], i32 1, <vscale x 4 x i1> [[MASK0]])
+; CHECK-NEXT: [[LOAD_1_0:%.*]] = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr [[TMP1]], i32 1, <vscale x 4 x i1> [[MASK1]], <vscale x 4 x float> [[PASSTHROUGH:%.*]])
+; CHECK-NEXT: ret <vscale x 4 x float> [[LOAD_1_0]]
+;
+ %mask0 = tail call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i32(i32 0, i32 8)
+ %mask1 = tail call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i32(i32 0, i32 4)
+ %load.0.0 = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr %0, i32 1, <vscale x 4 x i1> %mask0, <vscale x 4 x float> zeroinitializer)
+ %gep.0.16 = getelementptr i8, ptr %0, i32 16
+ %load.0.16 = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr %gep.0.16, i32 1, <vscale x 4 x i1> %mask0, <vscale x 4 x float> zeroinitializer)
+ %fmul = fmul <vscale x 4 x float> %load.0.0, %load.0.16
+ call void @llvm.masked.store.nxv4f32.p0(<vscale x 4 x float> %fmul, ptr %1, i32 1, <vscale x 4 x i1> %mask0)
+ %load.1.0 = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr %1, i32 1, <vscale x 4 x i1> %mask1, <vscale x 4 x float> %passthrough)
+ ret <vscale x 4 x float> %load.1.0
+}
+
+define <vscale x 4 x float> @store_mask_differs(ptr %0, ptr %1, <vscale x 4 x float> %passthrough) {
+; CHECK-LABEL: @store_mask_differs(
+; CHECK-NEXT: [[MASK0:%.*]] = tail call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i32(i32 0, i32 8)
+; CHECK-NEXT: [[MASK1:%.*]] = tail call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i32(i32 0, i32 4)
+; CHECK-NEXT: [[LOAD_0_0:%.*]] = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr [[TMP0:%.*]], i32 1, <vscale x 4 x i1> [[MASK0]], <vscale x 4 x float> zeroinitializer)
+; CHECK-NEXT: [[GEP_0_16:%.*]] = getelementptr i8, ptr [[TMP0]], i32 16
+; CHECK-NEXT: [[LOAD_0_16:%.*]] = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr [[GEP_0_16]], i32 1, <vscale x 4 x i1> [[MASK0]], <vscale x 4 x float> zeroinitializer)
+; CHECK-NEXT: [[FMUL:%.*]] = fmul <vscale x 4 x float> [[LOAD_0_0]], [[LOAD_0_16]]
+; CHECK-NEXT: call void @llvm.masked.store.nxv4f32.p0(<vscale x 4 x float> [[FMUL]], ptr [[TMP1:%.*]], i32 1, <vscale x 4 x i1> [[MASK1]])
+; CHECK-NEXT: [[LOAD_1_0:%.*]] = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr [[TMP1]], i32 1, <vscale x 4 x i1> [[MASK0]], <vscale x 4 x float> [[PASSTHROUGH:%.*]])
+; CHECK-NEXT: ret <vscale x 4 x float> [[LOAD_1_0]]
+;
+ %mask0 = tail call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i32(i32 0, i32 8)
+ %mask1 = tail call <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i32(i32 0, i32 4)
+ %load.0.0 = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr %0, i32 1, <vscale x 4 x i1> %mask0, <vscale x 4 x float> zeroinitializer)
+ %gep.0.16 = getelementptr i8, ptr %0, i32 16
+ %load.0.16 = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr %gep.0.16, i32 1, <vscale x 4 x i1> %mask0, <vscale x 4 x float> zeroinitializer)
+ %fmul = fmul <vscale x 4 x float> %load.0.0, %load.0.16
+ call void @llvm.masked.store.nxv4f32.p0(<vscale x 4 x float> %fmul, ptr %1, i32 1, <vscale x 4 x i1> %mask1)
+ %load.1.0 = call <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr %1, i32 1, <vscale x 4 x i1> %mask0, <vscale x 4 x float> %passthrough)
+ ret <vscale x 4 x float> %load.1.0
+}
+
+; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: read)
+declare <vscale x 4 x float> @llvm.masked.load.nxv4f32.p0(ptr captures(none), i32 immarg, <vscale x 4 x i1>, <vscale x 4 x float>) #1
+
+; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: write)
+declare void @llvm.masked.store.nxv4f32.p0(<vscale x 4 x float>, ptr captures(none), i32 immarg, <vscale x 4 x i1>) #2
+
+; Function Attrs: nocallback nofree nosync nounwind willreturn memory(none)
+declare <vscale x 4 x i1> @llvm.get.active.lane.mask.nxv4i1.i32(i32, i32) #3
+
----------------
artagnon wrote:
Unnecessary in recent LLVM?
https://github.com/llvm/llvm-project/pull/157689
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