================
@@ -660,14 +671,16 @@ void PPCAsmPrinter::EmitTlsCall(const MachineInstr *MI,
"GETtls[ld]ADDR[32] must read GPR3");
if (Subtarget->isAIXABI()) {
- // On AIX, the variable offset should already be in R4 and the region
handle
- // should already be in R3.
- // For TLSGD, which currently is the only supported access model, we only
- // need to generate an absolute branch to .__tls_get_addr.
+ // For TLSGD, the variable offset should already be in R4 and the region
+ // handle should already be in R3. We generate an absolute branch to
+ // .__tls_get_addr. For TLSLD, the module handle should already be in R3.
+ // We generate an absolute branch to .__tls_get_mod.
Register VarOffsetReg = Subtarget->isPPC64() ? PPC::X4 : PPC::R4;
(void)VarOffsetReg;
- assert(MI->getOperand(2).isReg() &&
- MI->getOperand(2).getReg() == VarOffsetReg &&
+ assert((MI->getOpcode() == PPC::GETtlsMOD32AIX ||
+ MI->getOpcode() == PPC::GETtlsMOD64AIX ||
+ (MI->getOperand(2).isReg() &&
+ MI->getOperand(2).getReg() == VarOffsetReg)) &&
"GETtls[ld]ADDR[32] must read GPR4");
EmitAIXTlsCallHelper(MI);
----------------
hubert-reinterpretcast wrote:
The helper functions have special calling convention properties. For example,
they do not use the FP registers. The IBM XL compiler was able to take
advantage of that.
For:
```c
__attribute__((tls_model("local-dynamic"))) __thread int x;
double g(int, double);
void f() {
double gg = g(0, 1.);
g(x, gg);
}
```
The IBM XL compilers were able to make use of the returned `double` staying in
the register:
```
28: 48 00 00 03 bla 0
00000028: R_RBA (idx: 36) .__tls_get_mod[PR]
2c: 7c 66 18 2e lwzx 3, 6, 3
30: 4b ff ff d1 bl 0x0 <.f>
00000030: R_RBR (idx: 34) .g[PR]
```
Clang/LLVM loads the value from the stack:
```
24: 48 00 00 03 bla 0
0000000000000024: R_RBA (idx: 3) .__tls_get_mod[PR]
28: e8 82 00 08 ld 4, 8(2)
000000000000002a: R_TOC (idx: 17) x[TC]
2c: 7c 63 22 aa lwax 3, 3, 4
30: 4b ff ff d1 bl 0x0 <.f>
0000000000000030: R_RBR (idx: 1) .g[PR]
```
https://github.com/llvm/llvm-project/pull/66316
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