[llvm] [InstCombine] Canonicalise SextADD + GEP (PR #69581)

[Nikita Popov via llvm-commits]

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@@ -10,20 +10,29 @@ define dso_local void @_Z3fooPiii(ptr %A, i32 %N, i32 %M) #0 {
 ; CHECK-NEXT:    [[CMP3:%.*]] = icmp sgt i32 [[N:%.*]], 0
 ; CHECK-NEXT:    [[CMP21:%.*]] = icmp sgt i32 [[M:%.*]], 0
 ; CHECK-NEXT:    [[OR_COND:%.*]] = select i1 [[CMP3]], i1 [[CMP21]], i1 false
-; CHECK-NEXT:    br i1 [[OR_COND]], label [[FOR_COND1_PREHEADER_LR_PH_SPLIT_US:%.*]], label [[FOR_COND_CLEANUP:%.*]]
-; CHECK:       for.cond1.preheader.lr.ph.split.us:
+; CHECK-NEXT:    br i1 [[OR_COND]], label [[FOR_COND1_PREHEADER_US_PREHEADER:%.*]], label [[FOR_COND_CLEANUP:%.*]]
+; CHECK:       for.cond1.preheader.us.preheader:
 ; CHECK-NEXT:    [[TMP0:%.*]] = zext i32 [[M]] to i64
-; CHECK-NEXT:    [[TMP1:%.*]] = zext i32 [[N]] to i64
-; CHECK-NEXT:    [[FLATTEN_TRIPCOUNT:%.*]] = mul nuw nsw i64 [[TMP0]], [[TMP1]]
+; CHECK-NEXT:    [[WIDE_TRIP_COUNT11:%.*]] = zext i32 [[N]] to i64
+; CHECK-NEXT:    [[WIDE_TRIP_COUNT:%.*]] = zext i32 [[M]] to i64
 ; CHECK-NEXT:    br label [[FOR_COND1_PREHEADER_US:%.*]]
 ; CHECK:       for.cond1.preheader.us:
-; CHECK-NEXT:    [[INDVAR6:%.*]] = phi i64 [ [[INDVAR_NEXT7:%.*]], [[FOR_COND1_PREHEADER_US]] ], [ 0, [[FOR_COND1_PREHEADER_LR_PH_SPLIT_US]] ]
-; CHECK-NEXT:    [[ARRAYIDX_US:%.*]] = getelementptr inbounds i32, ptr [[A:%.*]], i64 [[INDVAR6]]
-; CHECK-NEXT:    [[TMP2:%.*]] = load i32, ptr [[ARRAYIDX_US]], align 4
-; CHECK-NEXT:    tail call void @_Z1fi(i32 [[TMP2]])
-; CHECK-NEXT:    [[INDVAR_NEXT7]] = add nuw nsw i64 [[INDVAR6]], 1
-; CHECK-NEXT:    [[EXITCOND_NOT:%.*]] = icmp eq i64 [[INDVAR_NEXT7]], [[FLATTEN_TRIPCOUNT]]
-; CHECK-NEXT:    br i1 [[EXITCOND_NOT]], label [[FOR_COND_CLEANUP]], label [[FOR_COND1_PREHEADER_US]]
+; CHECK-NEXT:    [[INDVARS_IV7:%.*]] = phi i64 [ 0, [[FOR_COND1_PREHEADER_US_PREHEADER]] ], [ [[INDVARS_IV_NEXT8:%.*]], [[FOR_COND1_FOR_COND_CLEANUP3_CRIT_EDGE_US:%.*]] ]
+; CHECK-NEXT:    [[TMP1:%.*]] = mul nsw i64 [[INDVARS_IV7]], [[TMP0]]
+; CHECK-NEXT:    [[TMP2:%.*]] = getelementptr i32, ptr [[A:%.*]], i64 [[TMP1]]
+; CHECK-NEXT:    br label [[FOR_BODY4_US:%.*]]
+; CHECK:       for.body4.us:
+; CHECK-NEXT:    [[INDVARS_IV:%.*]] = phi i64 [ 0, [[FOR_COND1_PREHEADER_US]] ], [ [[INDVARS_IV_NEXT:%.*]], [[FOR_BODY4_US]] ]
+; CHECK-NEXT:    [[ARRAYIDX_US:%.*]] = getelementptr i32, ptr [[TMP2]], i64 [[INDVARS_IV]]
+; CHECK-NEXT:    [[TMP3:%.*]] = load i32, ptr [[ARRAYIDX_US]], align 4
+; CHECK-NEXT:    tail call void @_Z1fi(i32 [[TMP3]])
+; CHECK-NEXT:    [[INDVARS_IV_NEXT]] = add nuw nsw i64 [[INDVARS_IV]], 1
+; CHECK-NEXT:    [[EXITCOND_NOT:%.*]] = icmp eq i64 [[INDVARS_IV_NEXT]], [[WIDE_TRIP_COUNT]]
+; CHECK-NEXT:    br i1 [[EXITCOND_NOT]], label [[FOR_COND1_FOR_COND_CLEANUP3_CRIT_EDGE_US]], label [[FOR_BODY4_US]]
+; CHECK:       for.cond1.for.cond.cleanup3_crit_edge.us:
+; CHECK-NEXT:    [[INDVARS_IV_NEXT8]] = add nuw nsw i64 [[INDVARS_IV7]], 1
+; CHECK-NEXT:    [[EXITCOND12_NOT:%.*]] = icmp eq i64 [[INDVARS_IV_NEXT8]], [[WIDE_TRIP_COUNT11]]
+; CHECK-NEXT:    br i1 [[EXITCOND12_NOT]], label [[FOR_COND_CLEANUP]], label [[FOR_COND1_PREHEADER_US]]
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nikic wrote:

This is still a regression.

https://github.com/llvm/llvm-project/pull/69581