[llvm] [InstCombine][foldPHIArgGEPIntoPHI] Early return for const vector index for gep inst. (PR #138661)

[Nikita Popov via llvm-commits]

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@@ -0,0 +1,43 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+%vec = type { %vec_base }
+%vec_base = type { [4 x float] }
+%foo = type { %vec, %vec}
+
+define void @test(i1 %tobool, ptr addrspace(1) %add.ptr) {
+; CHECK-LABEL: define void @test(
+; CHECK-SAME: i1 [[TOBOOL:%.*]], ptr addrspace(1) [[ADD_PTR:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    [[LANE_0:%.*]] = alloca [[FOO:%.*]], align 16
+; CHECK-NEXT:    [[LANE_15:%.*]] = insertelement <16 x ptr> poison, ptr [[LANE_0]], i64 0
+; CHECK-NEXT:    br i1 [[TOBOOL]], label %[[F1:.*]], label %[[F0:.*]]
+; CHECK:       [[F0]]:
+; CHECK-NEXT:    [[MM_VECTORGEP:%.*]] = getelementptr inbounds [[FOO]], <16 x ptr> [[LANE_15]], <16 x i64> zeroinitializer, <16 x i32> splat (i32 1), <16 x i32> zeroinitializer, <16 x i32> zeroinitializer, <16 x i64> splat (i64 1)
+; CHECK-NEXT:    br label %[[MERGE:.*]]
+; CHECK:       [[F1]]:
+; CHECK-NEXT:    [[MM_VECTORGEP2:%.*]] = getelementptr inbounds [[FOO]], <16 x ptr> [[LANE_15]], <16 x i64> zeroinitializer, <16 x i32> zeroinitializer, <16 x i32> zeroinitializer, <16 x i32> zeroinitializer, <16 x i64> splat (i64 1)
+; CHECK-NEXT:    br label %[[MERGE]]
+; CHECK:       [[MERGE]]:
+; CHECK-NEXT:    [[VEC_PHI:%.*]] = phi <16 x ptr> [ [[MM_VECTORGEP]], %[[F0]] ], [ [[MM_VECTORGEP2]], %[[F1]] ]
+; CHECK-NEXT:    store <16 x ptr> [[VEC_PHI]], ptr addrspace(1) [[ADD_PTR]], align 128
+; CHECK-NEXT:    ret void
+;
+entry:
+  %lane.0 = alloca %foo, align 16
+  %lane.15 = insertelement <16 x ptr> poison, ptr %lane.0, i64 0
+  %mm_vectorGEP = getelementptr inbounds %foo, <16 x ptr> %lane.15, <16 x i64> zeroinitializer, <16 x i32> splat (i32 1), <16 x i32> zeroinitializer, <16 x i32> zeroinitializer, <16 x i64> splat (i64 1)
+  %mm_vectorGEP2 = getelementptr inbounds %foo, <16 x ptr> %lane.15, <16 x i64> zeroinitializer, <16 x i32> zeroinitializer, <16 x i32> zeroinitializer, <16 x i32> zeroinitializer, <16 x i64> splat (i64 1)
+  br i1 %tobool, label %f1, label %f0
+
+f0:
+  br label %merge
+
+f1:
+  br label %merge
+
+merge:
+  %vec.phi = phi <16 x ptr> [ %mm_vectorGEP, %f0], [ %mm_vectorGEP2, %f1 ]
+  store <16 x ptr> %vec.phi, ptr addrspace(1) %add.ptr
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nikic wrote:

Can replace the store with a return.

https://github.com/llvm/llvm-project/pull/138661