Represent runtime preemption in the IR.
Currently we do not represent runtime preemption in the IR, which has several
drawbacks:
1) The semantics of GlobalValues differ depending on the object file format
you are targeting (as well as the relocation-model and -fPIE value).
2) We have no way of disabling inlining of run time interposable functions,
since in the IR we only know if a function is link-time interposable.
Because of this llvm cannot support elf-interposition semantics.
3) In LTO builds of executables we will have extra knowledge that a symbol
resolved to a local definition and can't be preemptable, but have no way to
propagate that knowledge through the compiler.
This patch adds preemptability specifiers to the IR with the following meaning:
dso_local --> means the compiler may assume the symbol will resolve to a
definition within the current linkage unit and the symbol may be accessed
directly even if the definition is not within this compilation unit.
dso_preemptable --> means that the compiler must assume the GlobalValue may be
replaced with a definition from outside the current linkage unit at runtime.
To ease transitioning dso_preemptable is treated as a 'default' in that
low-level codegen will still do the same checks it did previously to see if a
symbol should be accessed indirectly. Eventually when IR producers emit the
specifiers on all Globalvalues we can change dso_preemptable to mean 'always
access indirectly', and remove the current logic.
Differential Revision: https://reviews.llvm.org/D20217
llvm-svn: 316668
diff --git a/llvm/test/CodeGen/PowerPC/preemption.ll b/llvm/test/CodeGen/PowerPC/preemption.ll
new file mode 100644
index 0000000..5652f6d
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/preemption.ll
@@ -0,0 +1,301 @@
+; RUN: llc -mtriple powerpc64le-unkown-gnu-linux < %s | FileCheck %s
+; RUN: llc -mtriple powerpc64le-unkown-gnu-linux -relocation-model=static \
+; RUN: < %s | FileCheck --check-prefix=STATIC %s
+; RUN: llc -mtriple powerpc64le-unkown-gnu-linux -relocation-model=pic \
+; RUN: < %s | FileCheck %s
+
+; globals
+
+@strong_default = global i32 55
+define i32* @get_strong_default() #0 {
+ ret i32* @strong_default
+
+; STATIC-LABEL: @get_strong_default
+; STATIC: addis 3, 2, strong_default@toc@ha
+; STATIC: addi 3, 3, strong_default@toc@l
+; STATIC: blr
+
+; CHECK-LABEL: @get_strong_default
+; CHECK: addis 3, 2, .LC0@toc@ha
+; CHECK: ld 3, .LC0@toc@l(3)
+; CHECK: blr
+}
+
+@weak_default = weak global i32 55
+define i32* @get_weak_default() #0 {
+ ret i32* @weak_default
+
+; STATIC-LABEL: @get_weak_default
+; STATIC: addis 3, 2, weak_default@toc@ha
+; STATIC: addi 3, 3, weak_default@toc@l
+; STATIC: blr
+
+; CHECK-LABEL: @get_weak_default
+; CHECK: addis 3, 2, .LC1@toc@ha
+; CHECK: ld 3, .LC1@toc@l(3)
+; CHECK: blr
+}
+
+@external_default_global = external global i32
+define i32* @get_external_default_global() {
+ ret i32* @external_default_global
+
+; STATIC-LABEL: @get_external_default_global
+; STATIC: addis 3, 2, .LC0@toc@ha
+; STATIC: ld 3, .LC0@toc@l(3)
+; STATIC: blr
+
+; CHECK-LABEL: @get_external_default_global
+; CHECK: addis 3, 2, .LC2@toc@ha
+; CHECK: ld 3, .LC2@toc@l(3)
+; CHECK: blr
+}
+
+
+@strong_local_global = dso_local global i32 55
+define i32* @get_strong_local_global() {
+ ret i32* @strong_local_global
+
+; STATIC-LABEL: @get_strong_local_global
+; STATIC: addis 3, 2, strong_local_global@toc@ha
+; STATIC: addi 3, 3, strong_local_global@toc@l
+; STATIC: blr
+
+; CHECK-LABEL: @get_strong_local_global
+; CHECK: addis 3, 2, strong_local_global@toc@ha
+; CHECK: addi 3, 3, strong_local_global@toc@l
+; CHECK: blr
+}
+
+@weak_local_global = weak dso_local global i32 42
+define i32* @get_weak_local_global() {
+ ret i32* @weak_local_global
+
+; STATIC-LABEL: @get_weak_local_global
+; STATIC: addis 3, 2, weak_local_global@toc@ha
+; STATIC: addi 3, 3, weak_local_global@toc@l
+; STATIC: blr
+
+; CHECK-LABEL: @get_weak_local_global
+; CHECK: addis 3, 2, weak_local_global@toc@ha
+; CHECK: addi 3, 3, weak_local_global@toc@l
+; CHECK: blr
+}
+
+@external_local_global = external dso_local global i32
+define i32* @get_external_local_global() {
+ ret i32* @external_local_global
+; STATIC-LABEL: @get_external_local_global
+; STATIC: addis 3, 2, external_local_global@toc@ha
+; STATIC: addi 3, 3, external_local_global@toc@l
+; STATIC: blr
+
+; CHECK-LABEL: @get_external_local_global
+; CHECK: addis 3, 2, external_local_global@toc@ha
+; CHECK: addi 3, 3, external_local_global@toc@l
+; CHECK: blr
+}
+
+@strong_preemptable_global = dso_preemptable global i32 42
+define i32* @get_strong_preemptable_global() {
+ ret i32* @strong_preemptable_global
+
+; STATIC-LABEL: @get_strong_preemptable_global
+; STATIC: addis 3, 2, strong_preemptable_global@toc@ha
+; STATIC: addi 3, 3, strong_preemptable_global@toc@l
+; STATIC: blr
+
+; CHECK-LABEL: @get_strong_preemptable_global
+; CHECK: addis 3, 2, .LC3@toc@ha
+; CHECK: ld 3, .LC3@toc@l(3)
+; CHECK: blr
+}
+
+@weak_preemptable_global = weak dso_preemptable global i32 42
+define i32* @get_weak_preemptable_global() {
+ ret i32* @weak_preemptable_global
+
+; STATIC-LABEL: @get_weak_preemptable_global
+; STATIC: addis 3, 2, weak_preemptable_global@toc@ha
+; STATIC: addi 3, 3, weak_preemptable_global@toc@l
+; STATIC: blr
+
+; CHECK-LABEL: @get_weak_preemptable_global
+; CHECK: addis 3, 2, .LC4@toc@ha
+; CHECK: ld 3, .LC4@toc@l(3)
+; CHECK: blr
+}
+
+@external_preemptable_global = external dso_preemptable global i32
+define i32* @get_external_preemptable_global() {
+ ret i32* @external_preemptable_global
+
+; STATIC-LABEL: @get_external_preemptable_global
+; STATIC: addis 3, 2, .LC1@toc@ha
+; STATIC: ld 3, .LC1@toc@l(3)
+; STATIC: blr
+
+; CHECK-LABEL: @get_external_preemptable_global
+; CHECK: addis 3, 2, .LC5@toc@ha
+; CHECK: ld 3, .LC5@toc@l(3)
+; CHECK: blr
+}
+
+; functions
+define signext i32 @strong_default_function(i32 %i) {
+ ret i32 %i
+}
+define signext i32 @strong_default_function_caller(i32 %i) {
+ %call = notail call signext i32 @strong_default_function(i32 signext %i)
+ ret i32 %call
+
+; STATIC-LABEL: @strong_default_function_caller
+; STATIC: bl strong_default_function
+; STATIC-NOT: nop
+; STATIC: blr
+
+; CHECK-LABEL: @strong_default_function_caller
+; CHECK: bl strong_default_function
+; CHECK-NEXT: nop
+; CHECK: blr
+}
+
+define weak signext i32 @weak_default_function(i32 %i) {
+ ret i32 %i
+}
+define signext i32 @weak_default_function_caller(i32 %i) {
+ %call = notail call signext i32 @weak_default_function(i32 signext %i)
+ ret i32 %call
+
+; STATIC-LABEL: @weak_default_function_caller
+; STATIC: bl weak_default_function
+; STATIC-NOT: nop
+; STATIC: blr
+
+; CHECK-LABEL: @weak_default_function_caller
+; CHECK: bl weak_default_function
+; CHECK-NEXT: nop
+; CHECK: blr
+}
+
+
+declare i32 @external_default_function(i32 %i)
+define i32 @external_default_function_caller(i32 %i) {
+ %call = notail call signext i32 @external_default_function(i32 signext %i)
+ ret i32 %call
+
+; STATIC-LABEL: @external_default_function_caller
+; STATIC: bl external_default_function
+; STATIC-NEXT: nop
+; STATIC: blr
+
+; CHECK-LABEL: @external_default_function_caller
+; CHECK: bl external_default_function
+; CHECK-NEXT: nop
+; CHECK: blr
+}
+
+define dso_local signext i32 @strong_local_function(i32 %i) {
+ ret i32 %i
+}
+define signext i32 @strong_local_function_caller(i32 %i) {
+ %call = notail call signext i32 @strong_local_function(i32 signext %i)
+ ret i32 %call
+
+; STATIC-LABEL: @strong_local_function_caller
+; STATIC: bl strong_local_function
+; STATIC-NOT: nop
+; STATIC: blr
+
+; CHECK-LABEL: @strong_local_function_caller
+; CHECK: bl strong_local_function
+; CHECK-NOT: nop
+; CHECK: blr
+}
+
+define weak dso_local signext i32 @weak_local_function(i32 %i) {
+ ret i32 %i
+}
+define signext i32 @weak_local_function_caller(i32 %i) {
+ %call = notail call signext i32 @weak_local_function(i32 signext %i)
+ ret i32 %call
+
+; STATIC-LABEL: @weak_local_function_caller
+; STATIC: bl weak_local_function
+; STATIC-NOT: nop
+; STATIC: blr
+
+; CHECK-LABEL: @weak_local_function_caller
+; CHECK: bl weak_local_function
+; CHECK-NOT: nop
+; CHECK: blr
+}
+
+declare dso_local i32 @external_local_function(i32 %i)
+define i32 @external_local_function_caller(i32 %i) {
+ %call = notail call signext i32 @external_local_function(i32 signext %i)
+ ret i32 %call
+
+; STATIC-LABEL: @external_local_function_caller
+; STATIC: bl external_local_function
+; STATIC-NOT: nop
+; STATIC: blr
+
+; CHECK-LABEL: @external_local_function_caller
+; CHECK: bl external_local_function
+; CHECK-NOT: nop
+; CHECK: blr
+}
+
+define dso_preemptable signext i32 @strong_preemptable_function(i32 %i) {
+ ret i32 %i
+}
+define signext i32 @strong_preemptable_function_caller(i32 %i) {
+ %call = notail call signext i32 @strong_preemptable_function(i32 signext %i)
+ ret i32 %call
+
+; STATIC-LABEL: @strong_preemptable_function_caller
+; STATIC: bl strong_preemptable_function
+; STATIC-NOT: nop
+; STATIC: blr
+
+; CHECK-LABEL: @strong_preemptable_function_caller
+; CHECK: bl strong_preemptable_function
+; CHECK-NEXT: nop
+; CHECK: blr
+}
+
+define weak dso_preemptable signext i32 @weak_preemptable_function(i32 %i) {
+ ret i32 %i
+}
+define signext i32 @weak_preemptable_function_caller(i32 %i) {
+ %call = notail call signext i32 @weak_preemptable_function(i32 signext %i)
+ ret i32 %call
+
+; STATIC-LABEL: @weak_preemptable_function_caller
+; STATIC: bl weak_preemptable_function
+; STATIC-NOT: nop
+; STATIC: blr
+
+; CHECK-LABEL: @weak_preemptable_function_caller
+; CHECK: bl weak_preemptable_function
+; CHECK-NEXT: nop
+; CHECK: blr
+}
+
+declare dso_preemptable i32 @external_preemptable_function(i32 %i)
+define i32 @external_preemptable_function_caller(i32 %i) {
+ %call = notail call signext i32 @external_preemptable_function(i32 signext %i)
+ ret i32 %call
+
+; STATIC-LABEL: @external_preemptable_function_caller
+; STATIC: bl external_preemptable_function
+; STATIC-NEXT: nop
+; STATIC: blr
+
+; CHECK-LABEL: @external_preemptable_function_caller
+; CHECK: bl external_preemptable_function
+; CHECK-NEXT: nop
+; CHECK: blr
+}
+