[PowerPC] [PR27387] Disallow r0 for ADD8TLS.

[• koriakin]

Summary

ADD8TLS, a variant of add instruction used for initial-exec TLS,
currently accepts r0 as a source register. While add itself supports
r0 just fine, linker can relax it to a local-exec sequence, converting
it to addi - which doesn't support r0.

This broke MemorySanitizer-powerpc64le :: signal_stress_test.cc.

[• koriakin]

Ping?

[hfinkel]

LGTM.

llvm/trunk/lib/Target/PowerPC/PPCInstr64Bit.td

def XORIS8  : DForm_4<27, (outs g8rc:$dst), (ins g8rc:$src1, u16imm64:$src2),
                       "xoris $dst, $src1, $src2", IIC_IntSimple,
                    [(set i64:$dst, (xor i64:$src1, imm16ShiftedZExt:$src2))]>;
 
 let isCommutable = 1 in
 defm ADD8  : XOForm_1r<31, 266, 0, (outs g8rc:$rT), (ins g8rc:$rA, g8rc:$rB),
                        "add", "$rT, $rA, $rB", IIC_IntSimple,
                        [(set i64:$rT, (add i64:$rA, i64:$rB))]>;
 // ADD8 has a special form: reg = ADD8(reg, sym@tls) for use by the
-// initial-exec thread-local storage model.
-def ADD8TLS  : XOForm_1<31, 266, 0, (outs g8rc:$rT), (ins g8rc:$rA, tlsreg:$rB),
+// initial-exec thread-local storage model.  We need to forbid r0 here -
+// while it works for add just fine, the linker can relax this to local-exec
+// addi, which won't work for r0.
+def ADD8TLS  : XOForm_1<31, 266, 0, (outs g8rc:$rT), (ins g8rc_nox0:$rA, tlsreg:$rB),
                         "add $rT, $rA, $rB", IIC_IntSimple,
                         [(set i64:$rT, (add i64:$rA, tglobaltlsaddr:$rB))]>;
                      
 let isCommutable = 1 in
 defm ADDC8 : XOForm_1rc<31, 10, 0, (outs g8rc:$rT), (ins g8rc:$rA, g8rc:$rB),
                         "addc", "$rT, $rA, $rB", IIC_IntGeneral,
                         [(set i64:$rT, (addc i64:$rA, i64:$rB))]>,
                         PPC970_DGroup_Cracked;

llvm/trunk/test/CodeGen/PowerPC/2016-04-16-ADD8TLS.ll

+; RUN: llc <%s | FileCheck %s
+target datalayout = "e-m:e-i64:64-n32:64"
+target triple = "powerpc64le-unknown-linux-gnu"
+
+@x = external thread_local global i32, align 4
+
+; Function Attrs: nounwind
+; CHECK-NOT: add [[REG1:[0-9]+]], 0, x@tls
+define void @f() {
+  %1 = tail call { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } asm sideeffect "nop", "={r3},={r4},={r5},={r6},={r7},={r8},={r9},={r10},={r11},={r12},={r14},={r15},={r16},={r17},={r18},={r19},={r20},={r21},={r22},={r23},={r24},={r25},={r26},={r27},={r28},={r29},={r30},~{memory}"()
+  %2 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 0
+  %3 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 1
+  %4 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 2
+  %5 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 3
+  %6 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 4
+  %7 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 5
+  %8 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 6
+  %9 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 7
+  %10 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 8
+  %11 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 9
+  %12 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 10
+  %13 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 11
+  %14 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 12
+  %15 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 13
+  %16 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 14
+  %17 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 15
+  %18 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 16
+  %19 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 17
+  %20 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 18
+  %21 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 19
+  %22 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 20
+  %23 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 21
+  %24 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 22
+  %25 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 23
+  %26 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 24
+  %27 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 25
+  %28 = extractvalue { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 } %1, 26
+  %29 = load i32, i32* @x, align 4
+  %30 = add nsw i32 %29, 1
+  store i32 %30, i32* @x, align 4
+  tail call void asm sideeffect "nop", "{r3},{r4},{r5},{r6},{r7},{r8},{r9},{r10},{r11},{r12},{r14},{r15},{r16},{r17},{r18},{r19},{r20},{r21},{r22},{r23},{r24},{r25},{r26},{r27},{r28},{r29},{r30},~{memory}"(i32 %2, i32 %3, i32 %4, i32 %5, i32 %6, i32 %7, i32 %8, i32 %9, i32 %10, i32 %11, i32 %12, i32 %13, i32 %14, i32 %15, i32 %16, i32 %17, i32 %18, i32 %19, i32 %20, i32 %21, i32 %22, i32 %23, i32 %24, i32 %25, i32 %26, i32 %27, i32 %28)
+  ret void
+}