[llvm] 5a052ef - Reapply "[SimplifyCFG] Forward indirect switch condition value if it can help fold the PHI (#95932)"
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Wed Jun 26 16:24:16 PDT 2024
Author: DianQK
Date: 2024-06-27T07:23:59+08:00
New Revision: 5a052ef76a95e525bc2fb0abdb68cefbe2d1a2ec
URL: https://github.com/llvm/llvm-project/commit/5a052ef76a95e525bc2fb0abdb68cefbe2d1a2ec
DIFF: https://github.com/llvm/llvm-project/commit/5a052ef76a95e525bc2fb0abdb68cefbe2d1a2ec.diff
LOG: Reapply "[SimplifyCFG] Forward indirect switch condition value if it can help fold the PHI (#95932)"
This reverts commit c7adfb5e715334c9de176f434088bd9f89aa9eb3.
Added:
Modified:
llvm/lib/Transforms/Utils/SimplifyCFG.cpp
llvm/test/CodeGen/AArch64/arm64-jumptable.ll
llvm/test/Transforms/SimplifyCFG/ForwardSwitchConditionToPHI.ll
llvm/test/Transforms/SimplifyCFG/Hexagon/switch-to-lookup-table.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 4e2dc7f2b2f4e..c52c4dc0b8a51 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -5818,7 +5818,8 @@ static bool ForwardSwitchConditionToPHI(SwitchInst *SI) {
for (auto &ForwardingNode : ForwardingNodes) {
PHINode *Phi = ForwardingNode.first;
SmallVectorImpl<int> &Indexes = ForwardingNode.second;
- if (Indexes.size() < 2)
+ // Check if it helps to fold PHI.
+ if (Indexes.size() < 2 && !llvm::is_contained(Phi->incoming_values(), SI->getCondition()))
continue;
for (int Index : Indexes)
diff --git a/llvm/test/CodeGen/AArch64/arm64-jumptable.ll b/llvm/test/CodeGen/AArch64/arm64-jumptable.ll
index 7d9adf92a6a95..40b8f721c0505 100644
--- a/llvm/test/CodeGen/AArch64/arm64-jumptable.ll
+++ b/llvm/test/CodeGen/AArch64/arm64-jumptable.ll
@@ -18,7 +18,7 @@ bb3:
bb4:
br label %exit.sink.split
exit.sink.split:
- %.sink = phi i32 [ 5, %bb4 ], [ %b, %bb1 ], [ 3, %bb3 ], [ %a, %entry ]
+ %.sink = phi i32 [ 5, %bb4 ], [ %b, %bb1 ], [ 7, %bb3 ], [ %a, %entry ]
store i32 %.sink, ptr %to
br label %exit
exit:
diff --git a/llvm/test/Transforms/SimplifyCFG/ForwardSwitchConditionToPHI.ll b/llvm/test/Transforms/SimplifyCFG/ForwardSwitchConditionToPHI.ll
index 5c266f4867398..8ad455eb9e7f2 100644
--- a/llvm/test/Transforms/SimplifyCFG/ForwardSwitchConditionToPHI.ll
+++ b/llvm/test/Transforms/SimplifyCFG/ForwardSwitchConditionToPHI.ll
@@ -59,6 +59,76 @@ return: ; preds = %entry, %sw.bb4, %sw
ret i32 %retval.0
}
+; We should not forward `%m` to 1, as this does not simplify the CFG.
+define i32 @forward_one(i32 %m) {
+; NO_FWD-LABEL: @forward_one(
+; NO_FWD-NEXT: entry:
+; NO_FWD-NEXT: switch i32 [[M:%.*]], label [[SW_BB4:%.*]] [
+; NO_FWD-NEXT: i32 0, label [[RETURN:%.*]]
+; NO_FWD-NEXT: i32 1, label [[SW_BB1:%.*]]
+; NO_FWD-NEXT: i32 2, label [[SW_BB2:%.*]]
+; NO_FWD-NEXT: i32 3, label [[SW_BB3:%.*]]
+; NO_FWD-NEXT: ]
+; NO_FWD: sw.bb1:
+; NO_FWD-NEXT: br label [[RETURN]]
+; NO_FWD: sw.bb2:
+; NO_FWD-NEXT: br label [[RETURN]]
+; NO_FWD: sw.bb3:
+; NO_FWD-NEXT: br label [[RETURN]]
+; NO_FWD: sw.bb4:
+; NO_FWD-NEXT: br label [[RETURN]]
+; NO_FWD: return:
+; NO_FWD-NEXT: [[RETVAL_0:%.*]] = phi i32 [ 4, [[SW_BB4]] ], [ 5, [[SW_BB3]] ], [ 6, [[SW_BB2]] ], [ 1, [[SW_BB1]] ], [ 8, [[ENTRY:%.*]] ]
+; NO_FWD-NEXT: ret i32 [[RETVAL_0]]
+;
+; FWD-LABEL: @forward_one(
+; FWD-NEXT: entry:
+; FWD-NEXT: switch i32 [[M:%.*]], label [[SW_BB4:%.*]] [
+; FWD-NEXT: i32 0, label [[RETURN:%.*]]
+; FWD-NEXT: i32 1, label [[SW_BB1:%.*]]
+; FWD-NEXT: i32 2, label [[SW_BB2:%.*]]
+; FWD-NEXT: i32 3, label [[SW_BB3:%.*]]
+; FWD-NEXT: ]
+; FWD: sw.bb1:
+; FWD-NEXT: br label [[RETURN]]
+; FWD: sw.bb2:
+; FWD-NEXT: br label [[RETURN]]
+; FWD: sw.bb3:
+; FWD-NEXT: br label [[RETURN]]
+; FWD: sw.bb4:
+; FWD-NEXT: br label [[RETURN]]
+; FWD: return:
+; FWD-NEXT: [[RETVAL_0:%.*]] = phi i32 [ 4, [[SW_BB4]] ], [ 5, [[SW_BB3]] ], [ 6, [[SW_BB2]] ], [ 1, [[SW_BB1]] ], [ 8, [[ENTRY:%.*]] ]
+; FWD-NEXT: ret i32 [[RETVAL_0]]
+;
+entry:
+ switch i32 %m, label %sw.bb4 [
+ i32 0, label %sw.bb0
+ i32 1, label %sw.bb1
+ i32 2, label %sw.bb2
+ i32 3, label %sw.bb3
+ ]
+
+sw.bb0: ; preds = %entry
+ br label %return
+
+sw.bb1: ; preds = %entry
+ br label %return
+
+sw.bb2: ; preds = %entry
+ br label %return
+
+sw.bb3: ; preds = %entry
+ br label %return
+
+sw.bb4: ; preds = %entry
+ br label %return
+
+return: ; preds = %entry, %sw.bb4, %sw.bb3, %sw.bb2, %sw.bb1
+ %retval.0 = phi i32 [ 4, %sw.bb4 ], [ 5, %sw.bb3 ], [ 6, %sw.bb2 ], [ 1, %sw.bb1 ], [ 8, %sw.bb0 ]
+ ret i32 %retval.0
+}
+
; If 1 incoming phi value is a case constant of a switch, convert it to the switch condition:
; https://bugs.llvm.org/show_bug.cgi?id=34471
; This then subsequently should allow squashing of the other trivial case blocks.
@@ -115,3 +185,60 @@ return:
ret i32 %r
}
+; We can replace `[ 1, %bb2 ]` with `[ %arg1, %bb2 ]`.
+define { i64, i64 } @PR95919(i64 noundef %arg, i64 noundef %arg1) {
+; NO_FWD-LABEL: @PR95919(
+; NO_FWD-NEXT: bb:
+; NO_FWD-NEXT: switch i64 [[ARG1:%.*]], label [[BB3:%.*]] [
+; NO_FWD-NEXT: i64 0, label [[BB5:%.*]]
+; NO_FWD-NEXT: i64 1, label [[BB2:%.*]]
+; NO_FWD-NEXT: ]
+; NO_FWD: bb2:
+; NO_FWD-NEXT: br label [[BB5]]
+; NO_FWD: bb3:
+; NO_FWD-NEXT: [[I:%.*]] = udiv i64 [[ARG:%.*]], [[ARG1]]
+; NO_FWD-NEXT: [[I4:%.*]] = shl nuw i64 [[I]], 1
+; NO_FWD-NEXT: br label [[BB5]]
+; NO_FWD: bb5:
+; NO_FWD-NEXT: [[I6:%.*]] = phi i64 [ [[I4]], [[BB3]] ], [ [[ARG]], [[BB2]] ], [ undef, [[BB:%.*]] ]
+; NO_FWD-NEXT: [[I7:%.*]] = phi i64 [ 1, [[BB3]] ], [ 1, [[BB2]] ], [ [[ARG1]], [[BB]] ]
+; NO_FWD-NEXT: [[I8:%.*]] = insertvalue { i64, i64 } poison, i64 [[I7]], 0
+; NO_FWD-NEXT: [[I9:%.*]] = insertvalue { i64, i64 } [[I8]], i64 [[I6]], 1
+; NO_FWD-NEXT: ret { i64, i64 } [[I9]]
+;
+; FWD-LABEL: @PR95919(
+; FWD-NEXT: bb:
+; FWD-NEXT: [[SWITCH:%.*]] = icmp ult i64 [[ARG1:%.*]], 2
+; FWD-NEXT: br i1 [[SWITCH]], label [[BB5:%.*]], label [[BB3:%.*]]
+; FWD: bb3:
+; FWD-NEXT: [[I:%.*]] = udiv i64 [[ARG:%.*]], [[ARG1]]
+; FWD-NEXT: [[I4:%.*]] = shl nuw i64 [[I]], 1
+; FWD-NEXT: br label [[BB5]]
+; FWD: bb5:
+; FWD-NEXT: [[I6:%.*]] = phi i64 [ [[I4]], [[BB3]] ], [ [[ARG]], [[BB:%.*]] ]
+; FWD-NEXT: [[I7:%.*]] = phi i64 [ 1, [[BB3]] ], [ [[ARG1]], [[BB]] ]
+; FWD-NEXT: [[I8:%.*]] = insertvalue { i64, i64 } poison, i64 [[I7]], 0
+; FWD-NEXT: [[I9:%.*]] = insertvalue { i64, i64 } [[I8]], i64 [[I6]], 1
+; FWD-NEXT: ret { i64, i64 } [[I9]]
+;
+bb:
+ switch i64 %arg1, label %bb3 [
+ i64 0, label %bb5
+ i64 1, label %bb2
+ ]
+
+bb2: ; preds = %bb
+ br label %bb5
+
+bb3: ; preds = %bb
+ %i = udiv i64 %arg, %arg1
+ %i4 = shl nuw i64 %i, 1
+ br label %bb5
+
+bb5: ; preds = %bb3, %bb2, %bb
+ %i6 = phi i64 [ %i4, %bb3 ], [ %arg, %bb2 ], [ undef, %bb ]
+ %i7 = phi i64 [ 1, %bb3 ], [ 1, %bb2 ], [ %arg1, %bb ]
+ %i8 = insertvalue { i64, i64 } poison, i64 %i7, 0
+ %i9 = insertvalue { i64, i64 } %i8, i64 %i6, 1
+ ret { i64, i64 } %i9
+}
diff --git a/llvm/test/Transforms/SimplifyCFG/Hexagon/switch-to-lookup-table.ll b/llvm/test/Transforms/SimplifyCFG/Hexagon/switch-to-lookup-table.ll
index 47dd24e194c39..b3b6abe314e6f 100644
--- a/llvm/test/Transforms/SimplifyCFG/Hexagon/switch-to-lookup-table.ll
+++ b/llvm/test/Transforms/SimplifyCFG/Hexagon/switch-to-lookup-table.ll
@@ -43,7 +43,7 @@ define i32 @foo(i32 %x) #0 section ".tcm_text" {
; DISABLE: sw.default:
; DISABLE-NEXT: br label [[RETURN]]
; DISABLE: return:
-; DISABLE-NEXT: [[RETVAL_0:%.*]] = phi i32 [ 19, [[SW_DEFAULT]] ], [ 5, [[SW_BB5]] ], [ 12, [[SW_BB4]] ], [ 22, [[SW_BB3]] ], [ 14, [[SW_BB2]] ], [ 20, [[SW_BB1]] ], [ 9, [[ENTRY:%.*]] ]
+; DISABLE-NEXT: [[RETVAL_0:%.*]] = phi i32 [ 19, [[SW_DEFAULT]] ], [ 33, [[SW_BB5]] ], [ 12, [[SW_BB4]] ], [ 22, [[SW_BB3]] ], [ 14, [[SW_BB2]] ], [ 20, [[SW_BB1]] ], [ 9, [[ENTRY:%.*]] ]
; DISABLE-NEXT: ret i32 [[RETVAL_0]]
;
entry:
@@ -81,7 +81,7 @@ sw.bb4: ; preds = %entry
br label %return
sw.bb5: ; preds = %entry
- store i32 5, ptr %retval, align 4
+ store i32 33, ptr %retval, align 4
br label %return
sw.default: ; preds = %entry
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