[llvm] [Loads] Support dereferenceable assumption with variable size. (PR #128436)
David Sherwood via llvm-commits
llvm-commits at lists.llvm.org
Mon Feb 24 01:53:50 PST 2025
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@@ -185,15 +185,32 @@ define void @deref_assumption_in_preheader_too_small_non_constant_trip_count_acc
; CHECK-NEXT: [[N_VEC:%.*]] = sub i64 [[N]], [[N_MOD_VF]]
; CHECK-NEXT: br label %[[VECTOR_BODY:.*]]
; CHECK: [[VECTOR_BODY]]:
-; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[PRED_LOAD_CONTINUE2:.*]] ]
; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[INDEX]], 0
-; CHECK-NEXT: [[TMP1:%.*]] = getelementptr i32, ptr [[A]], i64 [[TMP0]]
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds i32, ptr [[B]], i64 [[TMP0]]
; CHECK-NEXT: [[TMP3:%.*]] = getelementptr inbounds i32, ptr [[TMP2]], i32 0
; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <2 x i32>, ptr [[TMP3]], align 1
; CHECK-NEXT: [[TMP4:%.*]] = icmp sge <2 x i32> [[WIDE_LOAD]], zeroinitializer
-; CHECK-NEXT: [[TMP5:%.*]] = getelementptr i32, ptr [[TMP1]], i32 0
-; CHECK-NEXT: [[WIDE_LOAD1:%.*]] = load <2 x i32>, ptr [[TMP5]], align 1
+; CHECK-NEXT: [[TMP15:%.*]] = xor <2 x i1> [[TMP4]], splat (i1 true)
+; CHECK-NEXT: [[TMP5:%.*]] = extractelement <2 x i1> [[TMP15]], i32 0
+; CHECK-NEXT: br i1 [[TMP5]], label %[[PRED_LOAD_IF:.*]], label %[[PRED_LOAD_CONTINUE:.*]]
+; CHECK: [[PRED_LOAD_IF]]:
+; CHECK-NEXT: [[TMP16:%.*]] = getelementptr inbounds i32, ptr [[A]], i64 [[TMP0]]
+; CHECK-NEXT: [[TMP17:%.*]] = load i32, ptr [[TMP16]], align 1
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david-arm wrote:
I'm a bit confused. If you're increasing the number of places where we can treat the load as dereferenceable, why does it regress the code here to use conditional loads?
https://github.com/llvm/llvm-project/pull/128436
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