[PowerPC] Remove redundant TOC saves

This patch adds a peep hole optimization to remove any redundant toc save
instructions added as part of the call sequence for indirect calls. It removes
any toc saves within a function that are dominated by another toc save.

Differential Revision: https://reviews.llvm.org/D39736

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@319087 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 123 insertions, 0 deletions

diff --git a/test/CodeGen/PowerPC/remove-redundant-toc-saves.ll b/test/CodeGen/PowerPC/remove-redundant-toc-saves.ll
new file mode 100644
index 00000000000..8b9729544b8
--- /dev/null
+++ b/test/CodeGen/PowerPC/remove-redundant-toc-saves.ll
@@ -0,0 +1,123 @@
+; RUN: llc -verify-machineinstrs -mtriple=powerpc64le-unknown-linux-gnu < %s | FileCheck %s
+define signext i32 @test1(i32 signext %i, i32 (i32)* nocapture %Func, i32 (i32)* nocapture %Func2) {
+entry:
+; CHECK-LABEL: test1:
+; CHECK:    std 2, 24(1)
+; CHECK-NOT:    std 2, 24(1)
+  %call = tail call signext i32 %Func(i32 signext %i)
+  %call1 = tail call signext i32 %Func2(i32 signext %i)
+  %add2 = add nsw i32 %call1, %call
+  ret i32 %add2
+}
+
+define signext i32 @test2(i32 signext %i, i32 signext %j, i32 (i32)* nocapture %Func, i32 (i32)* nocapture %Func2) {
+entry:
+; CHECK-LABEL: test2:
+; CHECK:    std 2, 24(1)
+; CHECK-NOT:    std 2, 24(1)
+  %call = tail call signext i32 %Func(i32 signext %i)
+  %tobool = icmp eq i32 %j, 0
+  br i1 %tobool, label %if.end, label %if.then
+
+if.then:                                          ; preds = %entry
+  %call1 = tail call signext i32 %Func(i32 signext %i)
+  %add2 = add nsw i32 %call1, %call
+  %call3 = tail call signext i32 %Func2(i32 signext %i)
+  %add4 = add nsw i32 %add2, %call3
+  br label %if.end
+
+if.end:                                           ; preds = %entry, %if.then
+  %Sum.0 = phi i32 [ %add4, %if.then ], [ %call, %entry ]
+  %call5 = tail call signext i32 %Func(i32 signext %i)
+  %add6 = add nsw i32 %call5, %Sum.0
+  ret i32 %add6
+}
+
+; Check for multiple TOC saves with if then else where neither dominates the other.
+define signext i32 @test3(i32 signext %i, i32 (i32)* nocapture %Func, i32 (i32)* nocapture %Func2) {
+; CHECK-LABEL: test3:
+; CHECK:    std 2, 24(1)
+; CHECK:    std 2, 24(1)
+; CHECK-NOT:    std 2, 24(1)
+entry:
+  %tobool = icmp eq i32 %i, 0
+  br i1 %tobool, label %if.else, label %if.then
+
+if.then:                                          ; preds = %entry
+  %call = tail call signext i32 %Func(i32 signext %i)
+  br label %if.end
+
+if.else:                                          ; preds = %entry
+  %call1 = tail call signext i32 %Func2(i32 signext 0)
+  br label %if.end
+
+if.end:                                           ; preds = %if.else, %if.then
+  %Sum.0 = phi i32 [ %call, %if.then ], [ %call1, %if.else ]
+  %call3 = tail call signext i32 %Func(i32 signext %i)
+  %add4 = add nsw i32 %call3, %Sum.0
+  ret i32 %add4
+}
+
+define signext i32 @test4(i32 signext %i, i32 (i32)* nocapture %Func, i32 (i32)* nocapture %Func2) {
+; CHECK-LABEL: test4:
+; CHECK:    std 2, 24(1)
+; CHECK-NOT:    std 2, 24(1)
+
+entry:
+  %call = tail call signext i32 %Func(i32 signext %i)
+  %tobool = icmp eq i32 %i, 0
+  br i1 %tobool, label %if.else, label %if.then
+
+if.then:                                          ; preds = %entry
+  %call1 = tail call signext i32 %Func(i32 signext %i)
+  br label %if.end
+
+if.else:                                          ; preds = %entry
+  %call3 = tail call signext i32 %Func2(i32 signext 0)
+  br label %if.end
+
+if.end:                                           ; preds = %if.else, %if.then
+  %call1.pn = phi i32 [ %call1, %if.then ], [ %call3, %if.else ]
+  %Sum.0 = add nsw i32 %call1.pn, %call
+  ret i32 %Sum.0
+}
+
+; Check for multiple TOC saves with if then where neither is redundant.
+define signext i32 @test5(i32 signext %i, i32 (i32)* nocapture %Func, i32 (i32)* nocapture readnone %Func2) {
+entry:
+; CHECK-LABEL: test5:
+; CHECK:    std 2, 24(1)
+; CHECK:    std 2, 24(1)
+
+  %tobool = icmp eq i32 %i, 0
+  br i1 %tobool, label %if.end, label %if.then
+
+if.then:                                          ; preds = %entry
+  %call = tail call signext i32 %Func(i32 signext %i)
+  br label %if.end
+
+if.end:                                           ; preds = %entry, %if.then
+  %Sum.0 = phi i32 [ %call, %if.then ], [ 0, %entry ]
+  %call1 = tail call signext i32 %Func(i32 signext %i)
+  %add2 = add nsw i32 %call1, %Sum.0
+  ret i32 %add2
+}
+
+; Check for multiple TOC saves if there are dynamic allocations on the stack.
+define signext i32 @test6(i32 signext %i, i32 (i32)* nocapture %Func, i32 (i32)* nocapture %Func2) {
+entry:
+; CHECK-LABEL: test6:
+; CHECK:    std 2, 24(1)
+; CHECK:    std 2, 24(1)
+
+  %conv = sext i32 %i to i64
+  %0 = alloca i8, i64 %conv, align 16
+  %1 = bitcast i8* %0 to i32*
+  %call = tail call signext i32 %Func(i32 signext %i)
+  call void @useAlloca(i32* nonnull %1, i32 signext %call)
+  %call1 = call signext i32 %Func2(i32 signext %i)
+  %add2 = add nsw i32 %call1, %call
+  ret i32 %add2
+}
+
+declare void @useAlloca(i32*, i32 signext)