[Test] Add test showing missing opportunity of folding ICmp(Phi(Const…

…s...))

llvm/test/Transforms/InstCombine/icmp-constant-phi.ll

@@ -0,0 +1,135 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instcombine -S | FileCheck %s
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+; TODO: Replace with boolean Phi.
+
+define i1 @test_eq(i1 %cond) {
+; CHECK-LABEL: @test_eq(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[COND:%.*]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
+; CHECK:       if.true:
+; CHECK-NEXT:    br label [[MERGE:%.*]]
+; CHECK:       if.false:
+; CHECK-NEXT:    br label [[MERGE]]
+; CHECK:       merge:
+; CHECK-NEXT:    [[PHI:%.*]] = phi i32 [ 123, [[IF_TRUE]] ], [ 456, [[IF_FALSE]] ]
+; CHECK-NEXT:    br label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    [[COMPARE:%.*]] = icmp eq i32 [[PHI]], 456
+; CHECK-NEXT:    ret i1 [[COMPARE]]
+;
+entry:
+  br i1 %cond, label %if.true, label %if.false
+
+if.true:
+  br label %merge
+
+if.false:
+  br label %merge
+
+merge:
+  %phi = phi i32 [123, %if.true], [456, %if.false]
+  br label %exit
+
+exit:
+  %compare = icmp eq i32 %phi, 456
+  ret i1 %compare
+}
+
+define i1 @test_slt(i1 %cond) {
+; CHECK-LABEL: @test_slt(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[COND:%.*]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
+; CHECK:       if.true:
+; CHECK-NEXT:    br label [[MERGE:%.*]]
+; CHECK:       if.false:
+; CHECK-NEXT:    br label [[MERGE]]
+; CHECK:       merge:
+; CHECK-NEXT:    [[PHI:%.*]] = phi i32 [ 123, [[IF_TRUE]] ], [ 456, [[IF_FALSE]] ]
+; CHECK-NEXT:    br label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    [[COMPARE:%.*]] = icmp ult i32 [[PHI]], 456
+; CHECK-NEXT:    ret i1 [[COMPARE]]
+;
+entry:
+  br i1 %cond, label %if.true, label %if.false
+
+if.true:
+  br label %merge
+
+if.false:
+  br label %merge
+
+merge:
+  %phi = phi i32 [123, %if.true], [456, %if.false]
+  br label %exit
+
+exit:
+  %compare = icmp slt i32 %phi, 456
+  ret i1 %compare
+}
+
+define i1 @test_sle(i1 %cond) {
+; CHECK-LABEL: @test_sle(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[COND:%.*]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
+; CHECK:       if.true:
+; CHECK-NEXT:    br label [[MERGE:%.*]]
+; CHECK:       if.false:
+; CHECK-NEXT:    br label [[MERGE]]
+; CHECK:       merge:
+; CHECK-NEXT:    br label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret i1 true
+;
+entry:
+  br i1 %cond, label %if.true, label %if.false
+
+if.true:
+  br label %merge
+
+if.false:
+  br label %merge
+
+merge:
+  %phi = phi i32 [123, %if.true], [456, %if.false]
+  br label %exit
+
+exit:
+  %compare = icmp sle i32 %phi, 456
+  ret i1 %compare
+}
+
+define i1 @test_ne(i1 %cond) {
+; CHECK-LABEL: @test_ne(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[COND:%.*]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
+; CHECK:       if.true:
+; CHECK-NEXT:    br label [[MERGE:%.*]]
+; CHECK:       if.false:
+; CHECK-NEXT:    br label [[MERGE]]
+; CHECK:       merge:
+; CHECK-NEXT:    [[PHI:%.*]] = phi i32 [ 123, [[IF_TRUE]] ], [ 456, [[IF_FALSE]] ]
+; CHECK-NEXT:    br label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    [[COMPARE:%.*]] = icmp ne i32 [[PHI]], 456
+; CHECK-NEXT:    ret i1 [[COMPARE]]
+;
+entry:
+  br i1 %cond, label %if.true, label %if.false
+
+if.true:
+  br label %merge
+
+if.false:
+  br label %merge
+
+merge:
+  %phi = phi i32 [123, %if.true], [456, %if.false]
+  br label %exit
+
+exit:
+  %compare = icmp ne i32 %phi, 456
+  ret i1 %compare
+}