[InstCombine] re-commit r218721 with fix for pr21199

The icmp-select-icmp optimization targets select-icmp.eq
only. This is now ensured by testing the branch predicate
explictly. This commit also includes the test case for pr21199.

llvm-svn: 219282

3 files changed, 153 insertions, 1 deletions

diff --git a/llvm/test/Transforms/InstCombine/pr12338.ll b/llvm/test/Transforms/InstCombine/pr12338.ll
index d34600f0fa5..051c21ca41a 100644
--- a/llvm/test/Transforms/InstCombine/pr12338.ll
+++ b/llvm/test/Transforms/InstCombine/pr12338.ll
@@ -2,11 +2,11 @@
 
 define void @entry() nounwind {
 entry:
+; CHECK: br label %for.cond
   br label %for.cond
 
 for.cond:
   %local = phi <1 x i32> [ <i32 0>, %entry ], [ %phi2, %cond.end47 ]
-; CHECK: sub <1 x i32> <i32 92>, %local
   %phi3 = sub <1 x i32> zeroinitializer, %local
   br label %cond.end
 
diff --git a/llvm/test/Transforms/InstCombine/pr21199.ll b/llvm/test/Transforms/InstCombine/pr21199.ll
new file mode 100644
index 00000000000..e6599fb640d
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/pr21199.ll
@@ -0,0 +1,25 @@
+; do not replace a 'select' with 'or' in 'select - cmp - br' sequence
+; RUN: opt -instcombine -S < %s | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+declare void @f(i32)
+
+define void @test(i32 %len) {
+entry:
+  %cmp = icmp ult i32 %len, 8
+  %cond = select i1 %cmp, i32 %len, i32 8
+  %cmp11 = icmp ult i32 0, %cond
+  br i1 %cmp11, label %for.body, label %for.end
+
+for.body:                                         ; preds = %entry, %for.body
+  %i.02 = phi i32 [ %inc, %for.body ], [ 0, %entry ]
+  tail call void @f(i32 %cond)
+  %inc = add i32 %i.02, 1
+  %cmp1 = icmp ult i32 %inc, %cond
+  br i1 %cmp1, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+; CHECK: select
+}
diff --git a/llvm/test/Transforms/InstCombine/select-cmp-br.ll b/llvm/test/Transforms/InstCombine/select-cmp-br.ll
new file mode 100644
index 00000000000..2e999510b42
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/select-cmp-br.ll
@@ -0,0 +1,127 @@
+; Replace a 'select' with 'or' in 'select - cmp [eq|ne] - br' sequence
+; RUN: opt -instcombine -S < %s | FileCheck %s
+
+%C = type <{ %struct.S }>
+%struct.S = type { i64*, i32, i32 }
+
+declare void @bar(%struct.S *) #1
+
+define void @test1(%C*) {
+entry:
+  %1 = getelementptr inbounds %C* %0, i64 0, i32 0, i32 0
+  %m = load i64** %1, align 8
+  %2 = getelementptr inbounds %C* %0, i64 1, i32 0, i32 0
+  %n = load i64** %2, align 8
+  %3 = getelementptr inbounds i64* %m, i64 9
+  %4 = bitcast i64* %3 to i64 (%C*)**
+  %5 = load i64 (%C*)** %4, align 8
+  %6 = icmp eq i64* %m, %n
+  %7 = select i1 %6, %C* %0, %C* null
+  %8 = icmp eq %C* %7, null
+  br i1 %8, label %12, label %10
+
+; <label>:9                                       ; preds = %10, %12
+  ret void
+
+; <label>:10                                      ; preds = %entry
+  %11 = getelementptr inbounds %C* %7, i64 0, i32 0
+  tail call void @bar(%struct.S* %11)
+  br label %9
+
+; <label>:12                                      ; preds = %entry
+  %13 = tail call i64 %5(%C* %0)
+  br label %9
+; CHECK-LABEL: @test1(
+; CHECK-NOT: select
+; CHECK: or
+}
+
+define void @test2(%C*) {
+entry:
+  %1 = getelementptr inbounds %C* %0, i64 0, i32 0, i32 0
+  %m = load i64** %1, align 8
+  %2 = getelementptr inbounds %C* %0, i64 1, i32 0, i32 0
+  %n = load i64** %2, align 8
+  %3 = getelementptr inbounds i64* %m, i64 9
+  %4 = bitcast i64* %3 to i64 (%C*)**
+  %5 = load i64 (%C*)** %4, align 8
+  %6 = icmp eq i64* %m, %n
+  %7 = select i1 %6, %C* null, %C* %0
+  %8 = icmp eq %C* %7, null
+  br i1 %8, label %12, label %10
+
+; <label>:9                                       ; preds = %10, %12
+  ret void
+
+; <label>:10                                      ; preds = %entry
+  %11 = getelementptr inbounds %C* %7, i64 0, i32 0
+  tail call void @bar(%struct.S* %11)
+  br label %9
+
+; <label>:12                                      ; preds = %entry
+  %13 = tail call i64 %5(%C* %0)
+  br label %9
+; CHECK-LABEL: @test2(
+; CHECK-NOT: select
+; CHECK: or
+}
+
+define void @test3(%C*) {
+entry:
+  %1 = getelementptr inbounds %C* %0, i64 0, i32 0, i32 0
+  %m = load i64** %1, align 8
+  %2 = getelementptr inbounds %C* %0, i64 1, i32 0, i32 0
+  %n = load i64** %2, align 8
+  %3 = getelementptr inbounds i64* %m, i64 9
+  %4 = bitcast i64* %3 to i64 (%C*)**
+  %5 = load i64 (%C*)** %4, align 8
+  %6 = icmp eq i64* %m, %n
+  %7 = select i1 %6, %C* %0, %C* null
+  %8 = icmp ne %C* %7, null
+  br i1 %8, label %10, label %12
+
+; <label>:9                                       ; preds = %10, %12
+  ret void
+
+; <label>:10                                      ; preds = %entry
+  %11 = getelementptr inbounds %C* %7, i64 0, i32 0
+  tail call void @bar(%struct.S* %11)
+  br label %9
+
+; <label>:12                                      ; preds = %entry
+  %13 = tail call i64 %5(%C* %0)
+  br label %9
+; CHECK-LABEL: @test3(
+; CHECK-NOT: select
+; CHECK: or
+}
+
+define void @test4(%C*) {
+entry:
+  %1 = getelementptr inbounds %C* %0, i64 0, i32 0, i32 0
+  %m = load i64** %1, align 8
+  %2 = getelementptr inbounds %C* %0, i64 1, i32 0, i32 0
+  %n = load i64** %2, align 8
+  %3 = getelementptr inbounds i64* %m, i64 9
+  %4 = bitcast i64* %3 to i64 (%C*)**
+  %5 = load i64 (%C*)** %4, align 8
+  %6 = icmp eq i64* %m, %n
+  %7 = select i1 %6, %C* null, %C* %0
+  %8 = icmp ne %C* %7, null
+  br i1 %8, label %10, label %12
+
+; <label>:9                                       ; preds = %10, %12
+  ret void
+
+; <label>:10                                      ; preds = %entry
+  %11 = getelementptr inbounds %C* %7, i64 0, i32 0
+  tail call void @bar(%struct.S* %11)
+  br label %9
+
+; <label>:12                                      ; preds = %entry
+  %13 = tail call i64 %5(%C* %0)
+  br label %9
+; CHECK-LABEL: @test4(
+; CHECK-NOT: select
+; CHECK: or
+}