Implement builtin_{setjmp/longjmp} on PPC

This implements SJLJ lowering on PPC, making the Clang functions
__builtin_{setjmp/longjmp} functional on PPC platforms. The implementation
strategy is similar to that on X86, with the exception that a branch-and-link
variant is used to get the right jump address. Credit goes to Bill Schmidt for
suggesting the use of the unconditional bcl form (instead of the regular bl
instruction) to limit return-address-cache pollution.

Benchmarking the speed at -O3 of:

static jmp_buf env_sigill;

void foo() {
                __builtin_longjmp(env_sigill,1);
}

main() {
	...

        for (int i = 0; i < c; ++i) {
                if (__builtin_setjmp(env_sigill)) {
                        goto done;
                } else {
                        foo();
                }

done:;
        }

	...
}

vs. the same code using the libc setjmp/longjmp functions on a P7 shows that
this builtin implementation is ~4x faster with Altivec enabled and ~7.25x
faster with Altivec disabled. This comparison is somewhat unfair because the
libc version must also save/restore the VSX registers which we don't yet
support.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177666 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 108 insertions, 0 deletions

diff --git a/test/CodeGen/PowerPC/sjlj.ll b/test/CodeGen/PowerPC/sjlj.ll
new file mode 100644
index 0000000000..3440b314dd
--- /dev/null
+++ b/test/CodeGen/PowerPC/sjlj.ll
@@ -0,0 +1,108 @@
+; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr7 | FileCheck %s
+; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=a2 | FileCheck -check-prefix=CHECK-NOAV %s
+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-f128:128:128-v128:128:128-n32:64"
+target triple = "powerpc64-unknown-linux-gnu"
+
+%struct.__jmp_buf_tag = type { [64 x i64], i32, %struct.__sigset_t, [8 x i8] }
+%struct.__sigset_t = type { [16 x i64] }
+
+@env_sigill = internal global [1 x %struct.__jmp_buf_tag] zeroinitializer, align 16
+
+define void @foo() #0 {
+entry:
+  call void @llvm.eh.sjlj.longjmp(i8* bitcast ([1 x %struct.__jmp_buf_tag]* @env_sigill to i8*))
+  unreachable
+
+; CHECK: @foo
+; CHECK: addis [[REG:[0-9]+]], 2, env_sigill@toc@ha
+; CHECK: addi [[REG]], [[REG]], env_sigill@toc@l
+; CHECK: ld 31, 0([[REG]])
+; CHECK: ld [[REG2:[0-9]+]], 8([[REG]])
+; CHECK: ld 1, 16([[REG]])
+; CHECK: mtctr [[REG2]]
+; CHECK: ld 2, 24([[REG]])
+; CHECK: bctr
+
+return:                                           ; No predecessors!
+  ret void
+}
+
+declare void @llvm.eh.sjlj.longjmp(i8*) #1
+
+define signext i32 @main() #0 {
+entry:
+  %retval = alloca i32, align 4
+  store i32 0, i32* %retval
+  %0 = call i8* @llvm.frameaddress(i32 0)
+  store i8* %0, i8** bitcast ([1 x %struct.__jmp_buf_tag]* @env_sigill to i8**)
+  %1 = call i8* @llvm.stacksave()
+  store i8* %1, i8** getelementptr (i8** bitcast ([1 x %struct.__jmp_buf_tag]* @env_sigill to i8**), i32 2)
+  %2 = call i32 @llvm.eh.sjlj.setjmp(i8* bitcast ([1 x %struct.__jmp_buf_tag]* @env_sigill to i8*))
+  %tobool = icmp ne i32 %2, 0
+  br i1 %tobool, label %if.then, label %if.else
+
+if.then:                                          ; preds = %entry
+  store i32 1, i32* %retval
+  br label %return
+
+if.else:                                          ; preds = %entry
+  call void @foo()
+  br label %if.end
+
+if.end:                                           ; preds = %if.else
+  store i32 0, i32* %retval
+  br label %return
+
+return:                                           ; preds = %if.end, %if.then
+  %3 = load i32* %retval
+  ret i32 %3
+
+; CHECK: @main
+; CHECK: std
+; CHECK: stfd
+; CHECK: stvx
+
+; CHECK: addis [[REG:[0-9]+]], 2, env_sigill@toc@ha
+; CHECK: std 31, env_sigill@toc@l([[REG]])
+; CHECK: addi [[REG]], [[REG]], env_sigill@toc@l
+; CHECK: std [[REG]], [[OFF:[0-9]+]](31)                  # 8-byte Folded Spill
+; CHECK: std 1, 16([[REG]])
+; CHECK: std 2, 24([[REG]])
+; CHECK: bcl 20, 31, .LBB1_1
+; CHECK: li 3, 1
+; CHECK: #EH_SjLj_Setup	.LBB1_1
+; CHECK: b .LBB1_2
+
+; CHECK: .LBB1_1:
+; CHECK: mflr [[REGL:[0-9]+]]
+; CHECK: ld [[REG2:[0-9]+]], [[OFF]](31)                   # 8-byte Folded Reload
+; CHECK: std [[REGL]], 8([[REG2]])
+; CHECK: li 3, 0
+
+; CHECK: .LBB1_2:
+
+; CHECK: lfd
+; CHECK: lvx
+; CHECK: ld
+; CHECK: blr
+
+; CHECK-NOAV: @main
+; CHECK-NOAV-NOT: stvx
+; CHECK-NOAV: bcl
+; CHECK-NOAV: mflr
+; CHECK-NOAV: bl foo
+; CHECK-NOAV-NOT: lvx
+; CHECK-NOAV: blr
+}
+
+declare i8* @llvm.frameaddress(i32) #2
+
+declare i8* @llvm.stacksave() #3
+
+declare i32 @llvm.eh.sjlj.setjmp(i8*) #3
+
+attributes #0 = { nounwind "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-frame-pointer-elim-non-leaf"="true" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { noreturn nounwind }
+attributes #2 = { nounwind readnone }
+attributes #3 = { nounwind }
+