PowerPC: CTR shouldn't fire if a TLS call is in the loop

Determining the address of a TLS variable results in a function call in
certain TLS models.  This means that a simple ICmpInst might actually
result in invalidating the CTR register.

In such cases, do not attempt to rely on the CTR register for loop
optimization purposes.

This fixes PR22034.

Differential Revision: http://reviews.llvm.org/D6786

llvm-svn: 224890

1 files changed, 24 insertions, 1 deletions

diff --git a/llvm/test/CodeGen/PowerPC/ctrloops.ll b/llvm/test/CodeGen/PowerPC/ctrloops.ll
index ca00f687aa4..ccab7cb7a0b 100644
--- a/llvm/test/CodeGen/PowerPC/ctrloops.ll
+++ b/llvm/test/CodeGen/PowerPC/ctrloops.ll
@@ -1,6 +1,6 @@
 target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v128:128:128-n32:64"
 target triple = "powerpc64-unknown-freebsd10.0"
-; RUN: llc < %s -march=ppc64 | FileCheck %s
+; RUN: llc < %s -march=ppc64 -relocation-model=pic | FileCheck %s
 
 @a = common global i32 0, align 4
 
@@ -73,3 +73,26 @@ for.end:                                          ; preds = %for.body, %entry
 ; CHECK-NOT: cmplwi
 ; CHECK: bdnz
 }
+
+@tls_var = external thread_local global i8
+
+define i32 @test4() {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %phi = phi i32 [ %dec, %for.body ], [ undef, %entry ]
+  %load = ptrtoint i8* @tls_var to i32
+  %dec = add i32 %phi, -1
+  %cmp = icmp sgt i32 %phi, 1
+  br i1 %cmp, label %for.body, label %return
+
+return:                                           ; preds = %for.body
+  ret i32 %load
+; CHECK-LABEL: @test4
+; CHECK-NOT: mtctr
+; CHECK: addi {{[0-9]+}}
+; CHECK: cmpwi
+; CHECK-NOT: bdnz
+; CHECK: bgt
+}