Xqccmp: Left shift spimm in pop instructions (#775)

Shifting `spimm` left by 4 matches the behaviour of cm.push/cm.pop, and
moreover since qc.cm.push shifts by 4 the stack address is not
calculated correctly upon popping. E.g.

    qc.cm.push      {ra}, -64
    qc.cm.pop       {ra}, 64

will not recover the stack address in addition to loading incorrect
values for all saved registers.

Signed-off-by: Anton Johansson <[email protected]>
Co-authored-by: Anton Johansson <[email protected]>
Co-authored-by: ayosher <[email protected]>

Author: 3 people

arch_overlay/qc_iu/inst/Xqccmp/qc.cm.pop.yaml

@@ -24,6 +24,7 @@ encoding:
       not: [0, 1, 2, 3]
     - name: spimm
       location: 3-2
+      left_shift: 4
 access:
   s: always
   u: always
@@ -38,7 +39,7 @@ operation(): |
   XReg size = xlen() / 8;
   XReg nreg = (rlist == 15) ? 13 : (rlist - 3);
   XReg stack_aligned_adj = (nreg * size + 15) & ~0xF;
-  XReg virtual_address_new_sp = virtual_address_sp + stack_aligned_adj + spimm;
+  XReg virtual_address_new_sp = virtual_address_sp + stack_aligned_adj + (spimm `<< 4);
   XReg virtual_address_base = virtual_address_new_sp - size;
 
 

arch_overlay/qc_iu/inst/Xqccmp/qc.cm.popret.yaml

@@ -24,6 +24,7 @@ encoding:
       not: [0, 1, 2, 3]
     - name: spimm
       location: 3-2
+      left_shift: 4
 access:
   s: always
   u: always
@@ -38,7 +39,7 @@ operation(): |
   XReg size = xlen() / 8;
   XReg nreg = (rlist == 15) ? 13 : (rlist - 3);
   XReg stack_aligned_adj = (nreg * size + 15) & ~0xF;
-  XReg virtual_address_new_sp = virtual_address_sp + stack_aligned_adj + spimm;
+  XReg virtual_address_new_sp = virtual_address_sp + stack_aligned_adj + (spimm `<< 4);
   XReg virtual_address_base = virtual_address_new_sp - size;
 
 

arch_overlay/qc_iu/inst/Xqccmp/qc.cm.popretz.yaml

@@ -24,6 +24,7 @@ encoding:
       not: [0, 1, 2, 3]
     - name: spimm
       location: 3-2
+      left_shift: 4
 access:
   s: always
   u: always
@@ -38,7 +39,7 @@ operation(): |
   XReg size = xlen() / 8;
   XReg nreg = (rlist == 15) ? 13 : (rlist - 3);
   XReg stack_aligned_adj = (nreg * size + 15) & ~0xF;
-  XReg virtual_address_new_sp = virtual_address_sp + stack_aligned_adj + spimm;
+  XReg virtual_address_new_sp = virtual_address_sp + stack_aligned_adj + (spimm `<< 4);
   XReg virtual_address_base = virtual_address_new_sp - size;
 
   X[ 1] = read_memory_xlen(virtual_address_base -  0*size, $encoding);

arch_overlay/qc_iu/inst/Xqccmp/qc.cm.push.yaml

@@ -40,7 +40,7 @@ operation(): |
   XReg size = xlen() / 8;
   XReg nreg = (rlist == 15) ? 13 : (rlist - 3);
   XReg stack_aligned_adj = (nreg * size + 15) & ~0xF;
-  XReg virtual_address_new_sp = virtual_address_sp - stack_aligned_adj - spimm;
+  XReg virtual_address_new_sp = virtual_address_sp - stack_aligned_adj - (spimm `<< 4);
   XReg virtual_address_base = virtual_address_sp - size;
 
   write_memory_xlen(virtual_address_base -  0*size, X[ 1], $encoding);

arch_overlay/qc_iu/inst/Xqccmp/qc.cm.pushfp.yaml

@@ -26,6 +26,7 @@ encoding:
       not: [0, 1, 2, 3, 4]
     - name: spimm
       location: 3-2
+      left_shift: 4
 access:
   s: always
   u: always
@@ -40,7 +41,7 @@ operation(): |
   XReg size = xlen() / 8;
   XReg nreg = (rlist == 15) ? 13 : (rlist - 3);
   XReg stack_aligned_adj = (nreg * size + 15) & ~0xF;
-  XReg virtual_address_new_sp = virtual_address_sp - stack_aligned_adj - spimm;
+  XReg virtual_address_new_sp = virtual_address_sp - stack_aligned_adj - (spimm `<< 4);
   XReg virtual_address_base = virtual_address_sp - size;
 
   write_memory_xlen(virtual_address_base -  0*size, X[ 1], $encoding);