Switch to select optimization for two-case switches
This is the same optimization of r219233 with modifications to support PHIs with multiple incoming edges from the same block
and a test to check that this condition is handled.
llvm-svn: 219656
diff --git a/llvm/test/Transforms/SimplifyCFG/UnreachableEliminate.ll b/llvm/test/Transforms/SimplifyCFG/UnreachableEliminate.ll
index fc98746..21428c6 100644
--- a/llvm/test/Transforms/SimplifyCFG/UnreachableEliminate.ll
+++ b/llvm/test/Transforms/SimplifyCFG/UnreachableEliminate.ll
@@ -47,7 +47,7 @@
}
; PR9450
-define i32 @test4(i32 %v) {
+define i32 @test4(i32 %v, i32 %w) {
; CHECK: entry:
; CHECK-NEXT: switch i32 %v, label %T [
; CHECK-NEXT: i32 3, label %V
@@ -67,7 +67,7 @@
default:
unreachable
U:
- ret i32 1
+ ret i32 %w
T:
ret i32 2
}
diff --git a/llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll b/llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll
index 51ced40..97ce25fd1 100644
--- a/llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll
+++ b/llvm/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll
@@ -915,8 +915,12 @@
%x = phi i32 [ 3, %sw.default ], [ 7, %sw.bb1 ], [ 9, %entry ]
ret i32 %x
; CHECK-LABEL: @twocases(
-; CHECK: switch i32
+; CHECK-NOT: switch i32
; CHECK-NOT: @switch.table
+; CHECK: %switch.selectcmp
+; CHECK-NEXT: %switch.select
+; CHECK-NEXT: %switch.selectcmp1
+; CHECK-NEXT: %switch.select2
}
; Don't build tables for switches with TLS variables.
diff --git a/llvm/test/Transforms/SimplifyCFG/switch-to-select-multiple-edge-per-block-phi.ll b/llvm/test/Transforms/SimplifyCFG/switch-to-select-multiple-edge-per-block-phi.ll
new file mode 100644
index 0000000..ddf5d1f
--- /dev/null
+++ b/llvm/test/Transforms/SimplifyCFG/switch-to-select-multiple-edge-per-block-phi.ll
@@ -0,0 +1,40 @@
+; RUN: opt < %s -simplifycfg -S | FileCheck %s
+
+; a, b;
+; fn1() {
+; if (b)
+; if (a == 0 || a == 5)
+; return a;
+; return 0;
+; }
+
+; Checking that we handle correctly the case when we have a switch
+; branching multiple times to the same block
+
+@b = common global i32 0, align 4
+@a = common global i32 0, align 4
+
+; Function Attrs: nounwind
+define i32 @fn1() {
+; CHECK-LABEL: @fn1
+; CHECK: %switch.selectcmp1 = icmp eq i32 %1, 5
+; CHECK: %switch.select2 = select i1 %switch.selectcmp1, i32 5, i32 %switch.select
+entry:
+ %0 = load i32* @b, align 4
+ %tobool = icmp eq i32 %0, 0
+ br i1 %tobool, label %if.end3, label %if.then
+
+if.then:
+ %1 = load i32* @a, align 4
+ switch i32 %1, label %if.end3 [
+ i32 5, label %return
+ i32 0, label %return
+ ]
+
+if.end3:
+ br label %return
+
+return:
+ %retval.0 = phi i32 [ 0, %if.end3 ], [ %1, %if.then ], [ %1, %if.then ]
+ ret i32 %retval.0
+}
diff --git a/llvm/test/Transforms/SimplifyCFG/switch-to-select-two-case.ll b/llvm/test/Transforms/SimplifyCFG/switch-to-select-two-case.ll
new file mode 100644
index 0000000..69f97e5
--- /dev/null
+++ b/llvm/test/Transforms/SimplifyCFG/switch-to-select-two-case.ll
@@ -0,0 +1,72 @@
+; RUN: opt < %s -simplifycfg -S | FileCheck %s
+
+; int foo1_with_default(int a) {
+; switch(a) {
+; case 10:
+; return 10;
+; case 20:
+; return 2;
+; }
+; return 4;
+; }
+
+define i32 @foo1_with_default(i32 %a) {
+; CHECK-LABEL: @foo1_with_default
+; CHECK: %switch.selectcmp = icmp eq i32 %a, 20
+; CHECK-NEXT: %switch.select = select i1 %switch.selectcmp, i32 2, i32 4
+; CHECK-NEXT: %switch.selectcmp1 = icmp eq i32 %a, 10
+; CHECK-NEXT: %switch.select2 = select i1 %switch.selectcmp1, i32 10, i32 %switch.select
+entry:
+ switch i32 %a, label %sw.epilog [
+ i32 10, label %sw.bb
+ i32 20, label %sw.bb1
+ ]
+
+sw.bb:
+ br label %return
+
+sw.bb1:
+ br label %return
+
+sw.epilog:
+ br label %return
+
+return:
+ %retval.0 = phi i32 [ 4, %sw.epilog ], [ 2, %sw.bb1 ], [ 10, %sw.bb ]
+ ret i32 %retval.0
+}
+
+; int foo1_without_default(int a) {
+; switch(a) {
+; case 10:
+; return 10;
+; case 20:
+; return 2;
+; }
+; __builtin_unreachable();
+; }
+
+define i32 @foo1_without_default(i32 %a) {
+; CHECK-LABEL: @foo1_without_default
+; CHECK: %switch.selectcmp = icmp eq i32 %a, 10
+; CHECK-NEXT: %switch.select = select i1 %switch.selectcmp, i32 10, i32 2
+; CHECK-NOT: %switch.selectcmp1
+entry:
+ switch i32 %a, label %sw.epilog [
+ i32 10, label %sw.bb
+ i32 20, label %sw.bb1
+ ]
+
+sw.bb:
+ br label %return
+
+sw.bb1:
+ br label %return
+
+sw.epilog:
+ unreachable
+
+return:
+ %retval.0 = phi i32 [ 2, %sw.bb1 ], [ 10, %sw.bb ]
+ ret i32 %retval.0
+}