[Attributor] Make liveness "edge-based"

Summary:
If control is transferred to a successor is the key question when it
comes to liveness. The new implementation puts that question in the
focus and thereby providing a clean way to assume certain CFG edges are
dead or instructions will not transfer control.

Reviewers: sstefan1, uenoku

Subscribers: hiraditya, bollu, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69605

1 files changed, 73 insertions, 0 deletions

diff --git a/llvm/test/Transforms/FunctionAttrs/value-simplify.ll b/llvm/test/Transforms/FunctionAttrs/value-simplify.ll
index 2fbfa6cfa6b..29686f1eb7d 100644
--- a/llvm/test/Transforms/FunctionAttrs/value-simplify.ll
+++ b/llvm/test/Transforms/FunctionAttrs/value-simplify.ll
@@ -1,3 +1,4 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt -attributor --attributor-disable=false -S < %s | FileCheck %s
 ; TODO: Add max-iteration check
 ; ModuleID = 'value-simplify.ll'
@@ -119,3 +120,75 @@ end:
   ret void
 
 }
+
+define i32 @ipccp1(i32 %a) {
+; CHECK-LABEL: define {{[^@]+}}@ipccp1
+; CHECK-SAME: (i32 returned [[A:%.*]]) #0
+; CHECK-NEXT:    br i1 true, label [[T:%.*]], label [[F:%.*]]
+; CHECK:       t:
+; CHECK-NEXT:    ret i32 [[A:%.*]]
+; CHECK:       f:
+; CHECK-NEXT:    unreachable
+;
+  br i1 true, label %t, label %f
+t:
+  ret i32 %a
+f:
+  %r = call i32 @ipccp1(i32 5)
+  ret i32 %r
+}
+
+define internal i1 @ipccp2i(i1 %a) {
+; CHECK-LABEL: define {{[^@]+}}@ipccp2i
+; CHECK-SAME: (i1 returned [[A:%.*]]) #0
+; CHECK-NEXT:    br i1 true, label [[T:%.*]], label [[F:%.*]]
+; CHECK:       t:
+; CHECK-NEXT:    ret i1 true
+; CHECK:       f:
+; CHECK-NEXT:    unreachable
+;
+  br i1 %a, label %t, label %f
+t:
+  ret i1 %a
+f:
+  %r = call i1 @ipccp2i(i1 false)
+  ret i1 %r
+}
+
+define i1 @ipccp2() {
+; CHECK-LABEL: define {{[^@]+}}@ipccp2() #1
+; CHECK-NEXT:    [[R:%.*]] = call i1 @ipccp2i(i1 true) #0
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %r = call i1 @ipccp2i(i1 true)
+  ret i1 %r
+}
+
+define internal i32 @ipccp3i(i32 %a) {
+; CHECK-LABEL: define {{[^@]+}}@ipccp3i
+; CHECK-SAME: (i32 [[A:%.*]]) #1
+; CHECK-NEXT:    [[C:%.*]] = icmp eq i32 [[A:%.*]], 7
+; CHECK-NEXT:    br i1 [[C]], label [[T:%.*]], label [[F:%.*]]
+; CHECK:       t:
+; CHECK-NEXT:    ret i32 [[A]]
+; CHECK:       f:
+; CHECK-NEXT:    [[R:%.*]] = call i32 @ipccp3i(i32 5) #1
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %c = icmp eq i32 %a, 7
+  br i1 %c, label %t, label %f
+t:
+  ret i32 %a
+f:
+  %r = call i32 @ipccp3i(i32 5)
+  ret i32 %r
+}
+
+define i32 @ipccp3() {
+; CHECK-LABEL: define {{[^@]+}}@ipccp3() #1
+; CHECK-NEXT:    [[R:%.*]] = call i32 @ipccp3i(i32 7) #1
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %r = call i32 @ipccp3i(i32 7)
+  ret i32 %r
+}